feat(codebuddy): add CodeBuddy Code agent support

[Kayphoon]

Summary

• Adds first-class CodeBuddy Code support via rtk hook codebuddy and rtk init --agent codebuddy.
• Supports both project-local .codebuddy/settings.json hooks and the global CodeBuddy App/IDE marketplace plugin path.
• Adds clean install/uninstall behavior with docs and tests.

Why

This is an expanded implementation for #1966. It covers the CLI/settings hook path plus the CodeBuddy App/IDE plugin install path, including enabledPlugins handling. Related PR #1967 covers a smaller global settings integration; this PR is intended as the complete CodeBuddy agent support surface.

Changes

• Adds CodeBuddy CLI dispatch for rtk hook codebuddy, rtk init --agent codebuddy, and uninstall handling.
• Reuses the Claude-compatible PreToolUse command rewriting flow while leaving permission approval to the CodeBuddy host.
• Adds project/global settings patching, dry-run/manual patch output, plugin manifest and hook generation, idempotent install behavior, and uninstall cleanup.
• Updates README, hook documentation, and the supported agents guide for CodeBuddy.

Review Guide

Start with src/hooks/init.rs for install, plugin, and uninstall behavior. Then check src/hooks/hook_cmd.rs for the hook protocol output and src/main.rs for CLI dispatch. The docs changes mirror the new user-facing commands and can be reviewed after the behavior.

Test plan

• cargo fmt --all --check
• cargo test codebuddy
• cargo test --all
• cargo clippy --all-targets
• Manual temporary-HOME install/uninstall check for rtk init -g --agent codebuddy, including plugin files, enabledPlugins, idempotent reinstall, and cleanup of generated config.

Risk

Risk level: Medium.

Potential impact is localized to CodeBuddy config generation and CodeBuddy hook output. Existing agent integrations and telemetry paths are not changed.

Rollback plan: revert this commit.

Linked Issues

Closes #1966

Related: #1967

[rtk-release-bot]

This pull request has been automatically marked as stale due to 90 days of inactivity. If this pull request is still relevant, please leave any comment (for example, "bump"), and we'll keep it open. Your contribution is very much appreciated — we're sorry we haven't been able to review it yet.

[rtk-release-bot]

Closing this pull request after a prolonged period of inactivity. If this is still relevant, please ask for it to be reopened. Thank you!