feat: implement AI-assisted rename prompting feature

- Added data model for AI-assisted renaming including structures for prompts, responses, and policies.
- Created implementation plan detailing the integration of Google Genkit into the CLI for renaming tasks.
- Developed quickstart guide for setting up and using the new AI rename functionality.
- Documented research decisions regarding Genkit orchestration and prompt composition.
- Established tasks for phased implementation, including setup, foundational work, and user stories.
- Implemented contract tests to ensure AI rename policies and ledger metadata are correctly applied.
- Developed integration tests for validating AI rename flows, including preview, apply, and undo functionalities.
- Added tooling to pin Genkit dependency for consistent builds.

docs/CHANGELOG.md

@@ -9,3 +9,4 @@
 - Document quoting guidance, `--dry-run` / `--yes` behavior, and automation scenarios for replace command.
 - Add `renamer list` subcommand with shared scope flags and plain/table output formats.
 - Document global scope flags and hidden-file behavior.
+- Add `renamer ai` subcommand with export/import workflow, policy enforcement flags, prompt hash telemetry, and ledger metadata for applied plans.