UI overhaul "Living Codex" C+D: Lucide icons + left-rail shell

- Replace the top nav with a left rail + top context bar ("GM mission control"):
  gilt crown wordmark, nav grouped At the Table / Reference with Lucide icons and a
  gold active state (accent-glow + gilt left edge), a collapse toggle
  (uiStore.railCollapsed). A single responsive rail = icon strip (68px) on phones /
  when collapsed, full labels on >= sm.
- Top bar: campaign switcher, a ⌘K search pill, and every existing control preserved
  (PlayerSessionBadge, Session panel toggle, HandoutControl, SessionControl host,
  theme toggle as Sun/Moon, Settings) — same aria-labels/testids so e2e is intact.
- bun add lucide-react. Rail is print:hidden (sheets export clean).

223 unit + 34 e2e + 2 realtime green; nav contract (aria-label="Primary", link names) preserved.

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

package.json

@@ -27,6 +27,7 @@
     "dexie-react-hooks": "^1.1.7",
     "dompurify": "^3.2.3",
     "fuse.js": "^7.0.0",
+    "lucide-react": "^1.17.0",
     "nanoid": "^5.0.9",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",