conductor: add phase 6 context composition redesign tracks

- context_comp_decouple_20260510: Decouple Files & Media from Context Composition, directory grouping, file stats
- context_comp_slices_20260510: Slice visualization with annotations, view presets
- context_comp_presets_20260510: Context preset save/load with validation, context preview
- Depends_on chain: presets -> slices -> decouple

conductor/tracks/context_comp_decouple_20260510/metadata.json

@@ -0,0 +1,11 @@
+{
+  "id": "context_comp_decouple_20260510",
+  "title": "Context Composition Decoupling",
+  "phase": 6,
+  "created": "2026-05-10",
+  "status": "pending",
+  "spec_file": "spec.md",
+  "plan_file": "plan.md",
+  "depends_on": [],
+  "completion_checkpoints": []
+}