feat: presence beyond the tab — PWA manifest and the Ghost Log recap

Usability wave Workstream C (#5, #7):
- manifest.webmanifest with existing 192/512/180 icons, linked in
  index.html with theme-color aligned to #07070d; no service worker.
- GET /api/seances/recent: last 12 of the seeker's own séances with
  entity, per-kind event counts (one GROUP BY) and up to 3 spirit
  echoes (one windowed query) — no per-session N+1.
- /log Ghost Log page: cards with GhostGlyph, relative in-fiction
  timestamps, counts and echo lines; LOG link in the séance topbar;
  en/es i18n parity.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app/main.py

@@ -15,6 +15,7 @@ from app.routes.auth import router as auth_router
 from app.routes.codex import router as codex_router
 from app.routes.device import router as device_router
 from app.routes.inventory import router as inventory_router
+from app.routes.seances import router as seances_router
 from app.routes.shop import router as shop_router
 from app.session_cleanup import delete_expired_sessions
 from app.ws import AUDIO_DIR
@@ -97,6 +98,7 @@ app.include_router(auth_router)
 app.include_router(codex_router)
 app.include_router(device_router)
 app.include_router(inventory_router)
+app.include_router(seances_router)
 app.include_router(shop_router)
 app.include_router(ws_router)