feat(mobile): Thoughts in the mobile menu + full nav drawer on secondary pages

- Chat page: add "💭 Thoughts" to the mobile slide-out menu (with /thoughts handler),
  grouped with Journal. Thoughts was the one page mobile couldn't reach.
- nav.js: on mobile, secondary pages (Thoughts/Journal/Mind/Session/History/Hands/
  Logs) now get a ☰ slide-in drawer with the full nav + Settings — matching the
  desktop sidebar. Gated to pages without their own mobile menu, so the chat page's
  tailored hamburger/tab-bar is left untouched. Shared ITEMS list = one source of truth.

Static-only (no server change). 77 tests green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/web/static/index.html

@@ -41,9 +41,10 @@
       <h4>Actions</h4>
       <button id="mobileSessionBtn">🎬 Session HUD</button>
       <button id="mobileHistoryBtn">📚 Past Sessions</button>
+      <button id="mobileThoughtsBtn">💭 Thoughts</button>
+      <button id="mobileJournalBtn">📔 Journal</button>
       <button id="mobileThinkingStreamBtn">📜 Live Log (inline)</button>
       <button id="mobileFullLogBtn">⛶ Full Log</button>
-      <button id="mobileJournalBtn">📔 Journal</button>
       <button id="mobileSettingsBtn">⚙ Settings</button>
       <button id="mobileToggleThemeBtn">🌙 Toggle Theme</button>
       <button id="mobileForceReloadBtn">🔄 Force Reload</button>
@@ -1203,6 +1204,9 @@
       document.getElementById("mobileHistoryBtn").addEventListener("click", () => {
         closeMobileMenu(); window.location.href = "/history";
       });
+      document.getElementById("mobileThoughtsBtn").addEventListener("click", () => {
+        closeMobileMenu(); window.location.href = "/thoughts";
+      });
 
       // Connect to the global live log on page load.
       connectThinkingStream();