fix: avatar image overlays initials, chart canvas responsive sizing

Avatar bug:
- base.css: .lt-avatar now position:relative; img is position:absolute inset:0
  so a loaded image covers the initials span (fixes img+initials shown together)
- base.css: .lt-avatar img.lt-avatar-img-err { display:none } — CSS hook for error state
- layout_footer.php: capture-phase error event delegation on .lt-avatar imgs
  replaces blocked inline onerror handlers (CSP has no unsafe-inline in script-src)

Chart bug:
- DashboardView: replaced display:flex section-body containers with a
  position:relative; width:100%; height:170px div wrapper for each canvas
  (Chart.js responsive:true reads parentNode dimensions; flex containers
  give canvas zero intrinsic width causing 0×0 render = empty charts)
- Removed has-lt-overlay from chart frames (no overlay div was injected)

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

views/layout_footer.php

@@ -250,6 +250,16 @@
     })();
 <?php endif ?>
 
+    // ── Avatar image error fallback (CSP blocks inline onerror) ──────
+    // Uses capture-phase error delegation: if an img inside .lt-avatar
+    // fails to load, add .lt-avatar-img-err to hide it (CSS display:none),
+    // revealing the initials span underneath.
+    document.addEventListener('error', function(e) {
+      if (e.target.tagName === 'IMG' && e.target.closest('.lt-avatar')) {
+        e.target.classList.add('lt-avatar-img-err');
+      }
+    }, true);
+
     // Footer hint bar actions (keyboard help + settings — work on all pages)
     document.addEventListener('click', function(e) {
       var btn = e.target.closest('[data-action]');