T-10: Fix get_geo_batch_lookup for proper injection with GeoCache instance

Instead of returning a bound method (geo_cache.lookup_batch), now inject
the GeoCache instance directly into routers and services. This provides
proper runtime isolation since T-04 made GeoCache a proper object.

Changes:
- Remove get_geo_batch_lookup() dependency provider
- Add GeoCacheDep type alias for injecting GeoCache instances
- Update all routers (bans, blocklist, dashboard, jails) to use GeoCacheDep
- Update ban_service, blocklist_service, jail_service to accept GeoCache
- Update service protocols to match new signatures
- Update docstrings to reference GeoCache methods instead of module functions

All callers now call geo_cache.lookup_batch(...) directly instead of
geo_batch_lookup(...), providing real dependency injection with proper
testing isolation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/app/routers/bans.py

@@ -16,7 +16,7 @@ from app.dependencies import (
     AuthDep,
     DbDep,
     Fail2BanSocketDep,
-    GeoBatchLookupDep,
+    GeoCacheDep,
     HttpSessionDep,
 )
 from app.models.ban import ActiveBanListResponse, BanRequest, UnbanAllResponse, UnbanRequest
@@ -37,7 +37,7 @@ async def get_active_bans(
     db: DbDep,
     socket_path: Fail2BanSocketDep,
     http_session: HttpSessionDep,
-    geo_batch_lookup: GeoBatchLookupDep,
+    geo_cache: GeoCacheDep,
 ) -> ActiveBanListResponse:
     """Return every IP that is currently banned across all fail2ban jails.
 
@@ -56,7 +56,7 @@ async def get_active_bans(
     """
     return await ban_service.get_active_bans(
         socket_path,
-        geo_batch_lookup=geo_batch_lookup,
+        geo_cache=geo_cache,
         http_session=http_session,
         app_db=db,
     )