feat: Replace Playwright MCP with agent-browser CLI

- Remove Playwright MCP server from plugin
- Add new agent-browser skill for CLI-based browser automation
- Rename /playwright-test to /test-browser command
- Update all commands and agents to use agent-browser CLI
- Update README and plugin.json

agent-browser is Vercel's headless browser CLI designed for AI agents.
It uses ref-based selection (@e1, @e2) from accessibility snapshots
and provides a simpler CLI interface compared to MCP tools.

Key benefits:
- No MCP server required
- Simpler Bash-based workflow
- Same ref-based element selection
- Better for quick automation tasks

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

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

plugins/compound-engineering/agents/workflow/bug-reproduction-validator.md

@@ -19,7 +19,7 @@ When presented with a bug report, you will:
    - Set up the minimal test case needed to reproduce the issue
    - Execute the reproduction steps methodically, documenting each step
    - If the bug involves data states, check fixtures or create appropriate test data
-   - For UI bugs, consider using Playwright MCP if available to visually verify
+   - For UI bugs, use agent-browser CLI to visually verify (see `agent-browser` skill)
    - For backend bugs, examine logs, database states, and service interactions
 
 3. **Validation Methodology**: