Integrate agent-browser CLI as a lightweight browser automation tool.
Instead of embedding browser dependencies, this wraps the external
agent-browser binary via exec.Command, keeping PicoClaw lean.
Changes:
- Add BrowserTool (pkg/tools/browser.go) wrapping agent-browser CLI
- Add BrowserConfig to config with enabled, session, headless, timeout, cdp_port
- Register browser tool conditionally in agent loop
- Add unit tests for argument building, command splitting, error handling
The tool accepts a single 'command' parameter and delegates to agent-browser.
Default CDP port is 9222. Zero new Go dependencies - all stdlib imports.