docs: update README, README.zh-CN, SKILL.md for new Browser Bridge architecture

- Replace all Playwright MCP Bridge references with opencli Browser Bridge
- Remove token setup, MCP config, and manual setup sections
- Simplify prerequisites: just install extension, zero config
- Update troubleshooting: daemon status/logs commands
- Update env vars: add OPENCLI_DAEMON_PORT, OPENCLI_VERBOSE
- Update SKILL.md tags: mcp,playwright → chrome-extension,cdp