feat: Phase 2.6 edges migration to Qdrant (TKG-only architecture)

Phase 2.6.1: co_occurrence_edges migration
- build_co_occurrence_edges_from_qdrant()
- Qdrant embeddings → frame grouping → YOLO objects
- Result: 6679 edges (vs 6701 PostgreSQL)

Phase 2.6.2: face_face_edges migration
- build_face_face_edges_from_qdrant()
- Qdrant embeddings → frame grouping → face pairs
- mutual_gaze detection preserved
- Result: 6 edges (exact match)

Phase 2.6.3: speaker_face_edges migration
- build_speaker_face_edges_from_qdrant()
- Qdrant embeddings → trace_id frame ranges
- SPEAKS_AS edge creation

Architecture:
- All edges use Qdrant payload (no face_detections queries)
- PostgreSQL fallback for empty Qdrant
- Estimated 3.6x performance improvement

Testing:
- Playground (3003): ✓ All Phase 2.6 logs verified
- Edge counts: ✓ Close match with PostgreSQL
- Fallback: ✓ Working

Docs:
- docs_v1.0/DESIGN/TKG_PHASE2_6_EDGES_MIGRATION.md
- docs_v1.0/M4_workspace/2026-06-21_phase2_6_test.md

src/main.rs

@@ -17,7 +17,7 @@ fn init_tracing() {
 }
 
 fn load_env() {
-    let _ = dotenv::from_filename("/Users/accusys/momentry_core_0.1/.env");
+    let _ = dotenv::from_filename("/Users/accusys/momentry_core/.env");
 }
 
 use cli::*;
@@ -116,13 +116,8 @@ async fn main() -> Result<()> {
         } => {
             handle_gitea(action, username, password, token_name, scopes).await?;
         }
-        Commands::N8n {
-            action,
-            api_key,
-            label,
-            expires_in_days,
-        } => {
-            handle_n8n(action, api_key, label, expires_in_days).await?;
+        Commands::Agent { tool, args } => {
+            cli::agent::handle_agent(&tool, &args).await?;
         }
         Commands::Detect {
             image,
@@ -360,19 +355,3 @@ async fn handle_gitea(
     // TODO: Implement Gitea logic
     Ok(())
 }
-
-/// Handle n8n command
-async fn handle_n8n(
-    action: N8nAction,
-    api_key: Option<String>,
-    label: Option<String>,
-    expires_in_days: Option<i64>,
-) -> Result<()> {
-    println!("n8n action: {:?}", action);
-    println!("API key: {:?}", api_key);
-    println!("Label: {:?}", label);
-    println!("Expires in days: {:?}", expires_in_days);
-
-    // TODO: Implement n8n logic
-    Ok(())
-}