Support DevToolsActivePort CDP endpoints

[ffffhx]

Summary

• support direct browser WebSocket endpoints discovered from Chrome's DevToolsActivePort file when /json/version is unavailable
• allow BB_BROWSER_CDP_URL to provide an explicit ws:// or wss:// CDP browser endpoint
• pass the discovered browser WebSocket URL through CLI daemon startup and CdpConnection
• add a daemon startup regression test for DevToolsActivePort-only CDP access

Tests

• pnpm --filter @bb-browser/shared build && pnpm --filter @bb-browser/daemon build && pnpm --filter @bb-browser/cli build
• pnpm exec tsx --test --test-name-pattern 'managed port file|DevToolsActivePort' packages/cli/src/tests/daemon-startup.test.ts
• pnpm --filter @bb-browser/cli exec eslint src/cdp-discovery.ts src/daemon-manager.ts src/tests/daemon-startup.test.ts
• pnpm --filter @bb-browser/daemon exec eslint src/index.ts

Note: the full local pre-commit test suite was started, but an existing CLI startup test left a temporary Chrome/daemon process running and had to be terminated locally. The focused regression tests for this change passed.