feat: add --isolated flag to Playwright MCP for Claude Code provider

Added the --isolated flag to the Playwright MCP configuration to ensure
browser instances run in isolated contexts, preventing state leakage
between different agent sessions.

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

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

packages/server/src/server/agent/providers/claude-agent.ts

@@ -540,7 +540,7 @@ class ClaudeAgentSession implements AgentSession {
       playwright: {
         type: "stdio",
         command: "npx",
-        args: ["@playwright/mcp", "--headless"],
+        args: ["@playwright/mcp", "--headless", "--isolated"],
       },
     };