refactor(delegate-task): restructure category system for unbiased model selection

- Remove temperature from all categories
- Consolidate CATEGORY_MODEL_CATALOG into DEFAULT_CATEGORIES
- Replace 'general' and 'most-capable' with 'unspecified-low' and 'unspecified-high'
- Add Selection_Gate to unspecified categories to force deliberate selection
- Update quick category to use claude-haiku-4-5
- Update all references and tests across codebase

src/hooks/delegate-task-retry/index.ts

@@ -108,7 +108,7 @@ Example of CORRECT call:
 delegate_task(
   description="Task description",
   prompt="Detailed prompt...",
-  category="general",  // OR subagent_type="explore"
+  category="unspecified-low",  // OR subagent_type="explore"
   run_in_background=false,
   skills=[]
 )