Add Chrome headless diagnostic tool

Runs automatically when --chrome-headless flag is used, checking:
- ChromeDriver installation and PATH
- Chrome/Chromium installation
- Chrome and ChromeDriver version compatibility
- config.toml chrome_binary setting
- Chrome for Testing installation
- ChromeDriver executable permissions (macOS quarantine)

Displays a detailed report with:
- Summary of detected versions and paths
- Pass/warning/error status for each check
- Specific fix suggestions for any issues found

Users can then ask g3 to help fix any detected issues.

crates/g3-cli/Cargo.toml

@@ -8,6 +8,7 @@ description = "CLI interface for G3 AI coding agent"
 g3-core = { path = "../g3-core" }
 g3-config = { path = "../g3-config" }
 g3-planner = { path = "../g3-planner" }
+g3-computer-control = { path = "../g3-computer-control" }
 g3-providers = { path = "../g3-providers" }
 clap = { workspace = true }
 g3-ensembles = { path = "../g3-ensembles" }