feat: implement thumbnail generation and management

- Remove unused image dependencies from Cargo.lock.
- Update API to handle thumbnail generation and checkup processes.
- Introduce new routes for rebuilding and regenerating thumbnails.
- Enhance job tracking with progress indicators for thumbnail jobs.
- Update front-end components to display thumbnail job status and progress.
- Add backend logic for managing thumbnail jobs and integrating with the API.
- Refactor existing code to accommodate new thumbnail functionalities.

infra/migrations/0010_index_job_thumbnails_phase.sql

@@ -0,0 +1,6 @@
+-- Migration: Add status 'generating_thumbnails' for thumbnail phase after indexing
+
+ALTER TABLE index_jobs
+  DROP CONSTRAINT IF EXISTS index_jobs_status_check,
+  ADD CONSTRAINT index_jobs_status_check
+    CHECK (status IN ('pending', 'running', 'generating_thumbnails', 'success', 'failed'));