fix: lazy agent loading and type safety improvements

1. Lazy agent loading - fix race condition where prompts sent before initialization completes:
   - Add ensureAgentLoaded() helper that deduplicates initialization requests
   - Update handleSendAgentMessage/Audio to await agent initialization before streaming
   - Fix status updates being sent to client after initialization

2. Type safety - remove unsafe 'as any' casts for agent status:
   - Create AGENT_LIFECYCLE_STATUSES constant as single source of truth
   - Export AgentStatusSchema from messages.ts for reuse
   - Update registry schema to validate lastStatus against AgentStatusSchema
   - Add .default("closed") to handle missing status values from legacy files
   - Remove (record.lastStatus as any) cast in buildStoredAgentPayload

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

mcp-test-server.mjs

@@ -0,0 +1,67 @@
+import { createServer } from 'node:http';
+import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
+import { z } from 'zod';
+
+const mcpServer = new McpServer({ name: 'test', version: '0.0.1' });
+
+mcpServer.registerTool(
+  'fast_tool',
+  {
+    title: 'Fast tool',
+    description: 'Returns immediately',
+    inputSchema: {},
+    outputSchema: {
+      echo: z.string()
+    }
+  },
+  async () => {
+    console.log('[server] fast_tool handler invoked');
+    return {
+      content: [],
+      structuredContent: { echo: 'hello' }
+    };
+  }
+);
+
+mcpServer.registerTool(
+  'slow_tool',
+  {
+    title: 'Slow tool',
+    description: 'Waits before responding',
+    inputSchema: {
+      waitMs: z.number()
+    },
+    outputSchema: {
+      ok: z.boolean()
+    }
+  },
+  async ({ waitMs }) => {
+    console.log('[server] slow_tool handler invoked');
+    await new Promise(resolve => setTimeout(resolve, waitMs));
+    console.log('[server] slow_tool resolving');
+    return {
+      content: [],
+      structuredContent: { ok: true }
+    };
+  }
+);
+
+const transport = new StreamableHTTPServerTransport({ sessionIdGenerator: () => 'test-session' });
+await mcpServer.connect(transport);
+
+const HOST = '127.0.0.1';
+const PORT = 6768;
+
+const server = createServer(async (req, res) => {
+  if (req.url !== '/mcp') {
+    res.statusCode = 404;
+    res.end('not found');
+    return;
+  }
+  await transport.handleRequest(req, res);
+});
+
+server.listen(PORT, HOST, () => {
+  console.log(`Test MCP server listening on http://${HOST}:${PORT}`);
+});