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/routers/server.py

@@ -13,6 +13,7 @@ from __future__ import annotations
 from fastapi import APIRouter, Request, status
 
 from app.dependencies import AuthDep, Fail2BanSocketDep
+from app.mappers import server_mappers
 from app.models.server import ServerSettingsResponse, ServerSettingsUpdate
 from app.services import server_service
 
@@ -49,7 +50,8 @@ async def get_server_settings(
     Raises:
         HTTPException: 502 when fail2ban is unreachable.
     """
-    return await server_service.get_settings(socket_path)
+    domain_result = await server_service.get_settings(socket_path)
+    return server_mappers.map_domain_server_settings_result_to_response(domain_result)
 
 
 @router.put(