Fix HIGH priority issues: unbounded queries, rate limiting, health checks

Issue #3 - Unbounded Query Results (OOM):
- get_all_archived_history() now uses keyset pagination with bounded max_rows (50k default)
- Added 'id' field to records from get_archived_history() and get_archived_history_keyset()
- Protocol signature updated with page_size, max_rows, last_ban_id params

Issue #7 - Docker Health Check Fails:
- Added curl to Dockerfile.backend runtime image
- HEALTHCHECK now uses 'curl -f http://localhost:8000/api/health'
- compose.prod.yml: increased start_period to 40s, timeout to 10s
- Frontend healthcheck proxies to backend /api/health

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

backend/app/repositories/protocols.py

@@ -292,6 +292,9 @@ class HistoryArchiveRepository(Protocol):
         ip_filter: str | list[str] | None = None,
         origin: BanOrigin | None = None,
         action: str | None = None,
+        page_size: int = 1000,
+        max_rows: int = 50_000,
+        last_ban_id: int | None = None,
     ) -> list[dict[str, Any]]:
         ...