fix: address PR review comments for chroma server lifecycle

tests/infrastructure/graceful-shutdown.test.ts

@@ -87,6 +87,12 @@ describe('GracefulShutdown', () => {
         })
       };
 
+      const mockChromaServer = {
+        stop: mock(async () => {
+          callOrder.push('chromaServer.stop');
+        })
+      };
+
       // Create a PID file so we can verify it's removed
       writePidFile({ pid: 12345, port: 37777, startedAt: new Date().toISOString() });
       expect(existsSync(PID_FILE)).toBe(true);
@@ -95,16 +101,18 @@ describe('GracefulShutdown', () => {
         server: mockServer,
         sessionManager: mockSessionManager,
         mcpClient: mockMcpClient,
-        dbManager: mockDbManager
+        dbManager: mockDbManager,
+        chromaServer: mockChromaServer
       };
 
       await performGracefulShutdown(config);
 
-      // Verify order: PID removal happens first (synchronous), then server, then session, then MCP, then DB
+      // Verify order: PID removal happens first (synchronous), then server, then session, then MCP, then Chroma, then DB
       expect(callOrder).toContain('closeAllConnections');
       expect(callOrder).toContain('serverClose');
       expect(callOrder).toContain('sessionManager.shutdownAll');
       expect(callOrder).toContain('mcpClient.close');
+      expect(callOrder).toContain('chromaServer.stop');
       expect(callOrder).toContain('dbManager.close');
 
       // Verify server closes before session manager
@@ -115,6 +123,9 @@ describe('GracefulShutdown', () => {
 
       // Verify MCP closes before database
       expect(callOrder.indexOf('mcpClient.close')).toBeLessThan(callOrder.indexOf('dbManager.close'));
+
+      // Verify Chroma stops before DB closes
+      expect(callOrder.indexOf('chromaServer.stop')).toBeLessThan(callOrder.indexOf('dbManager.close'));
     });
 
     it('should remove PID file during shutdown', async () => {
@@ -184,7 +195,7 @@ describe('GracefulShutdown', () => {
       expect(mockSessionManager.shutdownAll).toHaveBeenCalledTimes(1);
     });
 
-    it('should close database after MCP client', async () => {
+    it('should stop chroma server before database close', async () => {
       const callOrder: string[] = [];
 
       const mockSessionManager: ShutdownableService = {
@@ -205,16 +216,23 @@ describe('GracefulShutdown', () => {
         })
       };
 
+      const mockChromaServer = {
+        stop: mock(async () => {
+          callOrder.push('chromaServer');
+        })
+      };
+
       const config: GracefulShutdownConfig = {
         server: null,
         sessionManager: mockSessionManager,
         mcpClient: mockMcpClient,
-        dbManager: mockDbManager
+        dbManager: mockDbManager,
+        chromaServer: mockChromaServer
       };
 
       await performGracefulShutdown(config);
 
-      expect(callOrder).toEqual(['sessionManager', 'mcpClient', 'dbManager']);
+      expect(callOrder).toEqual(['sessionManager', 'mcpClient', 'chromaServer', 'dbManager']);
     });
 
     it('should handle shutdown when PID file does not exist', async () => {