T-11: Validate repository Protocol structural compatibility — minimal approach (Option B)

Problem: Repository modules use structural typing to satisfy Protocol interfaces via
cast(). A function rename, parameter change, or signature mismatch would silently pass
mypy but fail at runtime.

Solution (Option B — minimal):
1. Aligned Protocol signatures in protocols.py with actual implementations:
   - BlocklistRepository: dict[str, object] → dict[str, Any] (matches implementation)
   - ImportLogRepository: dict[str, object] → ImportLogRow (typed model)
   - GeoCacheRepository: dict[str, object] → GeoCacheRow; Iterable → Sequence
   - HistoryArchiveRepository: dict[str, object] → dict[str, Any]
   - ImportLogRepository: async compute_total_pages → sync (matches implementation)

2. Created CI validation script (backend/scripts/validate_repository_protocols.py)
   that runs at build time to ensure all repository modules satisfy their Protocol
   interfaces. Exit 0 if valid, 1 if any mismatch. Detects:
   - Missing functions
   - Parameter count mismatches
   - Type annotation mismatches
   - Return type mismatches

3. Updated backend/app/dependencies.py with explicit docstrings linking each
   get_*_repo() provider to Backend-Development.md § 13.7.1, explaining the
   module-as-Protocol pattern and that it is intentional and validated.

4. Documented the pattern in Backend-Development.md § 13.7.1:
   'Repository Module Pattern — Module-as-Protocol Structural Compatibility'
   explaining why the pattern works, risks (silent breakage), and how the
   validation mitigates it.

5. Fixed type annotation in history_archive_repo.py:
   - get_all_archived_history returns list[dict] → list[dict[str, Any]]
   - Imported Any type

Benefits:
- Prevents silent breakage of repository interfaces
- Formalizes the module-as-Protocol pattern as intentional
- CI validation prevents regressions without refactoring cost
- All repository tests pass (53/53)
- mypy --strict passes on modified files

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

backend/app/repositories/history_archive_repo.py

@@ -7,7 +7,7 @@ application database.
 from __future__ import annotations
 
 import datetime
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from app.models.ban import BLOCKLIST_JAIL, BanOrigin
 
@@ -54,7 +54,7 @@ async def get_archived_history(
     action: str | None = None,
     page: int = 1,
     page_size: int = 100,
-) -> tuple[list[dict], int]:
+) -> tuple[list[dict[str, Any]], int]:
     """Return a paginated archived history result set."""
     if isinstance(ip_filter, list) and len(ip_filter) == 0:
         return [], 0
@@ -128,11 +128,11 @@ async def get_all_archived_history(
     ip_filter: str | list[str] | None = None,
     origin: BanOrigin | None = None,
     action: str | None = None,
-) -> list[dict]:
+) -> list[dict[str, Any]]:
     """Return all archived history rows for the given filters."""
     page: int = 1
     page_size: int = 500
-    all_rows: list[dict] = []
+    all_rows: list[dict[str, Any]] = []
 
     while True:
         rows, total = await get_archived_history(