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>

Docs/runner.csx

@@ -101,7 +101,8 @@ for (int i = 0; i < items.Count; i++)
     Console.WriteLine();
 
     // Step 1 — run the task prompt
-    await RunCopilot(Enumerable.Empty<string>(), $"read ./Docs/Instructions.md. {item}");
+    await RunCopilot(Enumerable.Empty<string>(), $"/caveman full");
+    await RunCopilot(new[] { "--continue" }, $"read ./Docs/Instructions.md. {item}");
     if (cts.IsCancellationRequested) break;
 
     // Step 2 — confirm completion in the same chat session
@@ -121,7 +122,9 @@ for (int i = 0; i < items.Count; i++)
 
     // Step 4 — commit the work
     Console.WriteLine("\n[runner] Task confirmed. Making git commit...\n");
-    await RunCopilot(Enumerable.Empty<string>(), "make git commit");
+
+    await RunCopilot(Enumerable.Empty<string>(), $"/caveman full");
+    await RunCopilot(new[] { "--continue" }, "make git commit");
     if (cts.IsCancellationRequested) break;
 
     // Step 5 — remove completed task from Tasks.md