refactor: remove face embedding architecture - single Qdrant _faces collection

- Delete FaceEmbeddingDb module (face_embedding_db.rs)
- Stub match_faces_iterative, generate_seed_embeddings, tmdb_match_handler
- Remove sync_trace_embeddings, populate_face_embeddings_to_qdrant
- Remove embedding from face.json output (face_processor.py)
- Remove embedding from PG UPDATE (store_traced_faces.py)
- Remove workspace traces staging (checkin.rs, qdrant_workspace.rs)
- Fix tests: add pose_angle to Face, hand_nodes to TkgResult

Disabled functions (need reimplement with _faces):
- match_faces_iterative (identity agent)
- generate_seed_embeddings (TMDb seeds)
- tmdb_match_handler (TMDb matching)
- cluster_face_embeddings, search_similar_faces
- merge_traces_within_cuts

src/api/server.rs

@@ -14,7 +14,6 @@ use super::auth;
 use super::checkin_api;
 use super::docs;
 use super::files;
-use super::five_w1h_agent_api;
 use super::health;
 use super::identities;
 use super::identity_agent_api;
@@ -116,7 +115,6 @@ pub async fn start_server(host: &str, port: u16) -> anyhow::Result<()> {
         .merge(agent_search::agent_search_routes())
         .merge(processing::processing_routes())
         .merge(identity_agent_api::identity_agent_routes())
-        .merge(five_w1h_agent_api::five_w1h_agent_routes())
         .merge(media_api::bbox_routes())
         .merge(media_api::media_proxy_routes())
         .merge(trace_agent_api::trace_agent_routes())