feat: automatic reconciliation loop for MCP server instances

mcpd now runs a periodic reconcileAll() every 30s that:
- Detects crashed/missing containers (syncStatus)
- Cleans up ERROR instances
- Creates replacement pods to match desired replica count

This replaces the old syncStatus-only timer. Servers migrated
from another deployment or recovering from node failures will
automatically get their instances recreated.

6 new tests for reconcileAll covering: missing instances, skip
replicas=0, already-at-count, ERROR cleanup, multi-server,
error isolation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/mcpd/src/services/instance.service.ts

@@ -107,6 +107,49 @@ export class InstanceService {
     return this.instanceRepo.findAll(serverId);
   }
 
+  /**
+   * Reconcile ALL servers — the operator loop.
+   *
+   * For every server with replicas > 0, ensures the correct number of
+   * healthy instances exist. Cleans up ERROR instances and starts
+   * replacements. This is the core self-healing mechanism.
+   */
+  async reconcileAll(): Promise<{ reconciled: number; errors: string[] }> {
+    await this.syncStatus();
+
+    const servers = await this.serverRepo.findAll();
+    let reconciled = 0;
+    const errors: string[] = [];
+
+    for (const server of servers) {
+      if (server.replicas <= 0) continue;
+
+      try {
+        const instances = await this.instanceRepo.findAll(server.id);
+        const active = instances.filter((i) => i.status === 'RUNNING' || i.status === 'STARTING');
+        const errored = instances.filter((i) => i.status === 'ERROR');
+
+        // Clean up ERROR instances so they don't accumulate
+        for (const inst of errored) {
+          await this.removeOne(inst);
+        }
+
+        // Scale up if needed
+        const toStart = server.replicas - active.length;
+        if (toStart > 0) {
+          for (let i = 0; i < toStart; i++) {
+            await this.startOne(server.id);
+          }
+          reconciled++;
+        }
+      } catch (err) {
+        errors.push(`${server.name}: ${err instanceof Error ? err.message : String(err)}`);
+      }
+    }
+
+    return { reconciled, errors };
+  }
+
   /**
    * Remove an instance (stop container + delete DB record).
    * Does NOT reconcile — caller should reconcile after if needed.