feat: Rule2 TKG relationship chunks + Phase0-1 Qdrant integration

Phase 0: TKG builder populate face_detections from face.json
- Fix face.json parser for pose_angle format
- Call store_traced_faces.py to set trace_id
- Skip if trace_id already populated

Phase 1: Qdrant face embeddings integration
- Add FaceEmbeddingDb module (src/core/db/face_embedding_db.rs)
- Create dev_face_embeddings collection (dim=512)
- Store 1122 face embeddings with pose metadata
- API: init_collection, batch_upsert, search_similar

Rule2: TKG edges → relationship chunks
- Design: RULE2_TKG_RELATIONSHIP_V1.0.md
- Implementation: rule2_ingest.rs
- ChunkType::Relationship added
- Edge types: SPEAKS_AS, MUTUAL_GAZE, CO_OCCURS_WITH, HAS_APPEARANCE, WEARS
- Auto-trigger on TKG rebuild

API:
- POST /api/v1/file/:file_uuid/rule2 (vectorization)
- POST /api/v1/file/:file_uuid/tkg/rebuild (auto Rule2)

Test: 75 relationship chunks created + vectorized

src/core/chunk/mod.rs

@@ -1,10 +1,12 @@
 pub mod rule1_ingest;
+pub mod rule2_ingest;
 pub mod rule3_ingest;
 pub mod splitter;
 pub mod trace_ingest;
 pub mod types;
 
 pub use rule1_ingest::execute_rule1;
+pub use rule2_ingest::ingest_rule2;
 pub use rule3_ingest::ingest_rule3;
 pub use splitter::{AsrSegment, ChunkSplitter};
 pub use trace_ingest::ingest_traces;