Fix welcome logo, real hex grid, Matrix boot messages, deeper TDS coverage

- WelcomePage: use official Lotus.png instead of generated SVG
- Hex Grid background: proper pointy-top hexagons via SVG data URI (was
  just triangles from linear-gradient trick)
- Boot sequence: Matrix-specific messages (TLS cert, E2EE Olm/Megolm,
  cross-signing, media proxy, /help hint)
- Terminal mode CSS: nav right border, header bottom glow, kbd TDS key
  style, abbr cyan underline, time amber color, img hover cyan outline,
  explicit body color anchor

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

src/lotus-boot.ts

@@ -1,20 +1,23 @@
 const BOOT_MESSAGES = [
   '╔════════════════════════════════════════════════════╗',
   '║      LOTUS CHAT  —  LOTUSGUILD PLATFORM            ║',
-  '║   SECURE MATRIX CLIENT  —  TERMINAL MODE ACTIVE    ║',
+  '║   SECURE MATRIX CLIENT — TERMINAL MODE ACTIVE      ║',
   '╚════════════════════════════════════════════════════╝',
   '',
   '[ OK ] Kernel modules loaded',
-  '[ OK ] Filesystem mounted read-write',
   '[ OK ] Network interfaces configured',
-  '[ OK ] Matrix homeserver connection established',
-  '[ OK ] End-to-end encryption initialized',
-  '[ OK ] Authentication service started',
-  '[ OK ] Security headers applied',
+  '[ OK ] DNS resolution active',
+  '[ OK ] TLS certificate verified — matrix.lotusguild.org',
+  '[ OK ] Matrix homeserver connected',
+  '[ OK ] E2EE Olm/Megolm keys loaded',
+  '[ OK ] Cross-signing keys verified',
   '[ OK ] Room state synchronized',
+  '[ OK ] Media proxy available',
+  '[ OK ] Notification service active',
   '[ OK ] Terminal interface rendered',
   '',
   '> ALL SYSTEMS NOMINAL — LOTUS CHAT',
+  '> TYPE /help FOR COMMANDS',
   '',
 ];