Add DevTools CDP handoff helpers

[anhtahaylove]

Summary

• add devtools_context MCP helper that returns CDP HTTP/WebSocket URLs plus /json/list page targets for a profile
• show DevTools/CDP ready on running profile rows and add copy actions for CDP HTTP / DevTools inspect URLs
• document the Codex + Chrome DevTools MCP handoff workflow

Notes

• no browser engine, fingerprint, profile isolation, token, cookie, or proxy credential behavior changes
• chrome_devtools attach stays at MCP client startup/configuration layer; Launcher core only exposes/copies existing CDP URLs

Tests

• node --check mcp/index.js
• npm run build
• cargo check --manifest-path src-tauri/Cargo.toml
• cargo test --manifest-path src-tauri/Cargo.toml --lib