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/config/schema.ts

@@ -174,9 +174,9 @@ export const BuiltinCategoryNameSchema = z.enum([
   "ultrabrain",
   "artistry",
   "quick",
-  "most-capable",
+  "unspecified-low",
+  "unspecified-high",
   "writing",
-  "general",
 ])
 
 export const CategoriesConfigSchema = z.record(z.string(), CategoryConfigSchema)