feat: back-port design system utilities from tinker_tickets to web_template

Sticky footer layout:
- body: add display:flex + flex-direction:column
- .lt-main: add flex:1 + width:100% + min-width:0 so it fills remaining height
- .lt-main.lt-container combined-selector specificity fix (prevents lt-container
  padding from overriding lt-main padding-top in responsive breakpoints)
- Responsive breakpoints updated to use .lt-main.lt-container combined selector

Modal utilities:
- .lt-modal-xs (280px), .lt-modal-sm (360px) — size modifiers
- .lt-modal-header--danger — danger variant (red bg tint + accent border/title)

Badge:
- .lt-badge-sm — compact size (0.5rem font, 0.05/0.3rem padding)

KV rows:
- .lt-kv-row (display:contents), .lt-kv-label, .lt-kv-value — alternate KV
  row pattern where children become direct lt-kv-grid items

Avatar image overlay:
- .lt-avatar: add position:relative so img can overlay initials
- .lt-avatar img: use absolute inset:0 overlay (was flat width/height)
- .lt-avatar img.lt-avatar-img-err: display:none when JS marks broken image

Extended markdown styles:
- list-style: disc/decimal + colored ::marker (cyan/orange)
- mark, del, sub, sup, task-item, task-cb, task-done, task-todo
- Footnote helpers: fn-ref, fn-hr, fn-list, fn-item, fn-back
- .md-image alias on img rule

Footer keyboard hints:
- .lt-footer-hints, .lt-footer-hint, .lt-footer-key, .lt-footer-sep

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

base.css

@@ -217,6 +217,8 @@ body {
   min-height: 100vh;
   overflow-x: hidden;
   position: relative;
+  display: flex;
+  flex-direction: column;
 }
 
 a {
@@ -350,6 +352,16 @@ hr {
 
 .lt-main {
   padding-top: calc(var(--header-height) + var(--space-lg));
+  flex: 1;
+  width: 100%;
+  min-width: 0;
+}
+/* When both lt-main and lt-container are on the same element, the lt-container
+   shorthand `padding` overrides the lt-main `padding-top` in responsive breakpoints
+   (same cascade specificity, later rule wins). The combined selector has higher
+   specificity (0,2,0 vs 0,1,0) and always wins regardless of source order. */
+.lt-main.lt-container {
+  padding-top: calc(var(--header-height) + var(--space-lg));
 }
 
 .lt-layout {
@@ -1215,6 +1227,7 @@ select option:checked {
 .lt-badge-green { color: var(--accent-green); }
 .lt-badge-amber { color: var(--accent-amber); }
 .lt-badge-red   { color: var(--accent-red); }
+.lt-badge-sm    { font-size: 0.5rem; padding: 0.05rem 0.3rem; }
 
 /* Status + priority badge variants (dark-mode base) */
 .lt-badge-open        { color: var(--accent-green);  background: rgba(0,255,136,0.08);  border-color: rgba(0,255,136,0.35);  text-shadow: var(--glow-green); }
@@ -1318,6 +1331,20 @@ select option:checked {
 .lt-modal-close:active { color: var(--accent-red); opacity: 0.7; }
 .lt-modal-close:focus-visible { outline: 2px solid var(--accent-cyan); outline-offset: 2px; border-radius: 2px; }
 
+/* Modal size modifiers */
+.lt-modal-xs { width: min(280px, 92vw); }
+.lt-modal-sm { width: min(360px, 92vw); }
+
+/* Modal header danger variant */
+.lt-modal-header--danger {
+  background: rgba(255, 77, 77, 0.08);
+  border-bottom-color: var(--accent-red);
+}
+.lt-modal-header--danger .lt-modal-title {
+  color: var(--accent-red);
+  text-shadow: var(--glow-red);
+}
+
 .lt-modal-body {
   padding: var(--space-lg);
   overflow-y: auto;
@@ -2054,7 +2081,7 @@ select option:checked {
 /* ── SM — phones 480–767px ── */
 @media (max-width: 767px) {
   :root { --header-height: 50px; }
-  .lt-main { padding-top: calc(50px + var(--space-md)); }
+  .lt-main, .lt-main.lt-container { padding-top: calc(50px + var(--space-md)); }
 
   .lt-container { padding: var(--space-md); }
   .lt-header { padding: 0 var(--space-md); }
@@ -2154,7 +2181,7 @@ select option:checked {
 /* ── XS — tiny phones ≤ 479px ── */
 @media (max-width: 479px) {
   :root { --header-height: 46px; }
-  .lt-main { padding-top: calc(46px + var(--space-sm)); }
+  .lt-main, .lt-main.lt-container { padding-top: calc(46px + var(--space-sm)); }
 
   .lt-container { padding: var(--space-sm); }
   .lt-stats-grid { grid-template-columns: 1fr 1fr; gap: var(--space-xs); }
@@ -3191,6 +3218,30 @@ input[type="range"].lt-range::-moz-range-thumb {
 .lt-kv-val--green  { color: var(--accent-green); }
 .lt-kv-val--red    { color: var(--accent-red); }
 
+/* lt-kv-row / lt-kv-label / lt-kv-value — alternate KV row pattern using
+   CSS `display: contents` so children become direct grid items of lt-kv-grid */
+.lt-kv-row {
+  display: contents;
+}
+.lt-kv-label {
+  padding: var(--space-xs) var(--space-md) var(--space-xs) 0;
+  color: var(--text-dim);
+  font-size: 0.75rem;
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+  white-space: nowrap;
+  border-bottom: 1px solid var(--border-dim);
+  align-self: center;
+}
+.lt-kv-value {
+  padding: var(--space-xs) 0 var(--space-xs) var(--space-md);
+  color: var(--text-primary);
+  border-bottom: 1px solid var(--border-dim);
+  min-width: 0;
+  overflow-wrap: break-word;
+  align-self: center;
+}
+
 
 /* ----------------------------------------------------------------
    43. HERO / BANNER SECTION
@@ -4568,8 +4619,19 @@ html[data-theme="light"] .lt-sla-p2 { background: rgba(138,90,0,0.06);  border-c
   overflow: hidden;
   flex-shrink: 0;
   user-select: none;
+  position: relative; /* needed so img can overlay initials absolutely */
 }
-.lt-avatar img { width: 100%; height: 100%; object-fit: cover; display: block; }
+/* Image overlays initials — hidden by JS (.lt-avatar-img-err) when broken */
+.lt-avatar img {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  display: block;
+}
+/* When the image fails, JS adds .lt-avatar-img-err to hide it, revealing initials */
+.lt-avatar img.lt-avatar-img-err { display: none; }
 /* Sizes */
 .lt-avatar--xs { width: 1.5rem; height: 1.5rem; font-size: 0.55rem; }
 .lt-avatar--sm { width: 2rem;   height: 2rem;   font-size: 0.65rem; }
@@ -5183,7 +5245,23 @@ html[data-theme="light"] .lt-sla-p2 { background: rgba(138,90,0,0.06);  border-c
 .lt-markdown a:hover { text-decoration: underline; }
 .lt-markdown a:focus-visible { outline: 2px solid var(--accent-cyan); outline-offset: 2px; }
 .lt-markdown strong { color: var(--text-primary); }
-.lt-markdown img { max-width: 100%; border: 1px solid var(--border-dim); }
+.lt-markdown img, .md-image { max-width: 100%; height: auto; border: 1px solid var(--border-dim); border-radius: 2px; display: block; margin: 0.5rem 0; }
+.lt-markdown ul { list-style: disc; }
+.lt-markdown ol { list-style: decimal; }
+.lt-markdown ul li::marker { color: var(--accent-cyan); }
+.lt-markdown ol li::marker { color: var(--accent-orange); }
+.lt-markdown mark { background: var(--accent-yellow-dim, #2a2500); color: var(--accent-yellow, #e6c619); padding: 0 3px; border-radius: 2px; }
+.lt-markdown del { color: var(--text-muted); text-decoration: line-through; }
+.lt-markdown sub, .lt-markdown sup { font-size: 0.7em; line-height: 0; }
+.lt-markdown .task-item { list-style: none; margin-left: -1.2em; }
+.lt-markdown .task-cb  { margin-right: 0.35em; font-size: 1em; }
+.lt-markdown .task-done { color: var(--text-muted); text-decoration: line-through; }
+.lt-markdown .task-todo { color: var(--text-secondary); }
+.lt-markdown .fn-ref a { color: var(--accent-cyan); font-size: 0.7em; text-decoration: none; }
+.lt-markdown .fn-hr    { margin: 1rem 0 0.5rem; }
+.lt-markdown .fn-list  { font-size: 0.75rem; color: var(--text-muted); list-style: decimal; padding-left: 1.25rem; margin: 0; }
+.lt-markdown .fn-item  { margin-bottom: 0.2rem; }
+.lt-markdown .fn-back  { color: var(--accent-cyan); text-decoration: none; font-size: 0.85em; }
 .lt-markdown table { width: 100%; border-collapse: collapse; font-size: 0.78rem; margin: 0.75rem 0; }
 .lt-markdown th  { background: var(--bg-secondary); color: var(--accent-cyan); padding: 0.4rem 0.6rem; border: 1px solid var(--border-dim); text-align: left; font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.08em; }
 .lt-markdown td  { padding: 0.35rem 0.6rem; border: 1px solid var(--border-dim); color: var(--text-secondary); }
@@ -5606,6 +5684,33 @@ html[data-theme="light"] .lt-sla-p2 { background: rgba(138,90,0,0.06);  border-c
   .lt-footer { flex-direction: column; align-items: flex-start; gap: 0.25rem; }
 }
 
+/* Footer keyboard hint strip — a row of clickable key+label hints */
+.lt-footer-hints { display: flex; align-items: center; flex-wrap: wrap; gap: 0.25rem; }
+
+.lt-footer-hint {
+  all: unset;
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  gap: 0.25rem;
+  color: var(--text-muted);
+  font-size: 0.7rem;
+  font-family: var(--font-mono);
+  white-space: nowrap;
+}
+.lt-footer-hint:hover { color: var(--accent-cyan); }
+.lt-footer-hint:focus-visible { outline: 1px dashed var(--accent-cyan); outline-offset: 2px; }
+
+.lt-footer-key {
+  color: var(--accent-cyan);
+  opacity: 0.8;
+}
+
+.lt-footer-sep {
+  color: var(--border-dim);
+  user-select: none;
+}
+
 /* ================================================================
    BLINKING CURSOR
    <h1 class="lt-cursor">SYSTEM STATUS</h1>