Feat default surface routing + fix startup hang (#4)

Default surface routing (v0.2.1):
- `/` redirects to configurable default surface with fallback chain:
  configured → first enabled extension surface → /admin
- Auto-sets default_surface on first extension surface install
- Admin settings UI: Default Surface dropdown
- disabledRedirect() and extension surface disabled redirect now go to
  /admin instead of / to prevent redirect loops

Fix Gin route param conflict causing backend startup hang:
- Team package settings routes used `:pkgId` while sibling routes used
  `:id` — Gin's radix tree entered infinite loop on conflicting param
  names. Unified to `:id`.

Docker entrypoint hardening:
- Health check timeout 10s → 60s
- Stale backend process cleanup on restart
- Crash detection (exit early if backend dies)

Roadmap direction updates:
- v0.3.0: Notes surface (Obsidian-style) replaces Editor surface
- v0.4.0: MVP (was v0.5.0) — chat moved to post-MVP
- No built-in auto-install — explicit install only

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-entrypoint.sh

@@ -22,19 +22,29 @@ fi
 
 echo "🔀 Starting Switchboard Core backend..."
 
+# Kill any stale backend from a previous entrypoint run
+pkill -f /usr/local/bin/switchboard 2>/dev/null || true
+sleep 0.2
+
 # Launch Go backend in background (from /app so migrations are found)
 cd /app
 /usr/local/bin/switchboard &
 BACKEND_PID=$!
 
-# Wait for backend to be ready (max 10s)
-for i in $(seq 1 20); do
+# Wait for backend to be ready (max 60s)
+for i in $(seq 1 120); do
     if wget -q --spider http://localhost:${PORT:-8080}${BASE_PATH}/health 2>/dev/null; then
         echo "✅ Backend ready (PID ${BACKEND_PID})"
         exit 0
     fi
+    # Check backend didn't crash
+    if ! kill -0 ${BACKEND_PID} 2>/dev/null; then
+        echo "❌ Backend process died"
+        exit 1
+    fi
     sleep 0.5
 done
 
-echo "❌ Backend failed to start within 10s"
+echo "❌ Backend failed to start within 60s"
+kill ${BACKEND_PID} 2>/dev/null || true
 exit 1