Task 8: Standardize modeling style (TypedDict vs Pydantic)

Convert inconsistent modeling style to standardized Pydantic models for all
external-facing data structures while maintaining TypedDict compatibility where
appropriate for internal layer-private structures.

Changes:
- Converted IpLookupResult TypedDict to use IpLookupResponse Pydantic model
  in jail_service.lookup_ip() for consistency with routers
- Added GeoCacheEntry Pydantic model for geo cache repository rows
- Converted GeoCacheRow TypedDict to use GeoCacheEntry alias
- Converted ImportLogRow TypedDict to use ImportLogEntry alias
- Updated routers and services to work with Pydantic models
- Updated all tests to use Pydantic model field access (attributes)
  instead of dict subscripting

Documentation:
- Added 'Model Type Usage by Layer' section to Backend-Development.md
- Defines when TypedDict is allowed (internal structures) vs Pydantic
  (external-facing, cross-boundary data)
- Provides clear guidance on modeling conventions per layer

Benefits:
- Consistent validation and serialization behavior
- Better IDE support and type checking
- Clearer separation of concerns by layer
- Reduced maintenance cost from mixed validation approaches

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

backend/app/services/jail_service.py

@@ -18,14 +18,14 @@ from __future__ import annotations
 import asyncio
 import contextlib
 import ipaddress
-from typing import TYPE_CHECKING, TypedDict, cast
+from typing import TYPE_CHECKING, cast
 
 import structlog
 
 from app.exceptions import JailNotFoundError, JailOperationError
 from app.models.ban import ActiveBan, JailBannedIpsResponse
 from app.models.config import BantimeEscalation
-from app.models.geo import GeoDetail
+from app.models.geo import GeoDetail, IpLookupResponse
 from app.models.jail import (
     Jail,
     JailDetailResponse,
@@ -63,18 +63,6 @@ log: structlog.stdlib.BoundLogger = structlog.get_logger()
 
 __all__ = ["reload_all"]
 
-class IpLookupResult(TypedDict):
-    """Result returned by :func:`lookup_ip`.
-
-    This is intentionally a :class:`TypedDict` to provide precise typing for
-    callers (e.g. routers) while keeping the implementation flexible.
-    """
-
-    ip: str
-    currently_banned_in: list[str]
-    geo: GeoDetail | None
-
-
 # ---------------------------------------------------------------------------
 # Constants
 # ---------------------------------------------------------------------------
@@ -998,7 +986,7 @@ async def lookup_ip(
     ip: str,
     geo_enricher: GeoEnricher | None = None,
     http_session: aiohttp.ClientSession | None = None,
-) -> IpLookupResult:
+) -> IpLookupResponse:
     """Return ban status and history for a single IP address.
 
     Checks every running jail for whether the IP is currently banned.
@@ -1075,11 +1063,11 @@ async def lookup_ip(
 
     log.info("ip_lookup_completed", ip=ip, banned_in_jails=currently_banned_in)
 
-    return {
-        "ip": ip,
-        "currently_banned_in": currently_banned_in,
-        "geo": geo,
-    }
+    return IpLookupResponse(
+        ip=ip,
+        currently_banned_in=currently_banned_in,
+        geo=geo,
+    )
 
 
 async def unban_all_ips(socket_path: str) -> int: