fix: face group name read consistency, sync_file_status fix, cleanup ghost records, identity_agent replaced with face_dedup

- get_face_groups_handler: COALESCE(tp.name, tn.label) for name consistency
- sync_file_status: compare JSON vs pre_chunks (not chunk table)
- face consistency: compare frames.len() not total_faces
- cleanup 2 ghost records with NULL file_name/file_path
- replace identity_agent with face_dedup in pipeline stages
- remove identity_agent_api.rs and all references
- update required_processors to match actual processors
- update AGENTS.md with team responsibilities
- add Studio pipeline changes documentation

migrations/037_add_completed_at_to_videos.sql

@@ -0,0 +1,12 @@
+-- Add completed_at timestamp to videos table
+-- This field tracks when file processing was completed
+
+ALTER TABLE public.videos ADD COLUMN IF NOT EXISTS completed_at timestamp with time zone;
+
+-- Create index for completed_at queries
+CREATE INDEX IF NOT EXISTS idx_videos_completed_at ON public.videos(completed_at);
+
+-- Update existing completed files to set completed_at = updated_at
+UPDATE public.videos 
+SET completed_at = updated_at 
+WHERE status = 'completed' AND completed_at IS NULL;