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>

Docker/compose.prod.yml

@@ -72,11 +72,11 @@ services:
     expose:
       - "8000"
     healthcheck:
-      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:8000/api/health')"]
+      test: ["CMD", "curl", "-f", "http://localhost:8000/api/health"]
       interval: 30s
-      timeout: 5s
-      start_period: 10s
+      timeout: 10s
       retries: 3
+      start_period: 40s
     networks:
       - bangui-net
 
@@ -93,11 +93,11 @@ services:
       backend:
         condition: service_healthy
     healthcheck:
-      test: ["CMD", "wget", "-qO", "/dev/null", "http://localhost:80/"]
+      test: ["CMD", "curl", "-f", "http://localhost:8000/api/health"]
       interval: 30s
-      timeout: 5s
-      start_period: 5s
+      timeout: 10s
       retries: 3
+      start_period: 5s
     networks:
       - bangui-net