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/shared/migration.test.ts

@@ -325,7 +325,7 @@ describe("migrateAgentConfigToCategory", () => {
       { model: "anthropic/claude-sonnet-4-5" },
     ]
 
-    const expectedCategories = ["visual-engineering", "ultrabrain", "quick", "most-capable", "general"]
+    const expectedCategories = ["visual-engineering", "ultrabrain", "quick", "unspecified-high", "unspecified-low"]
 
     // #when: Migrate each config
     const results = configs.map(migrateAgentConfigToCategory)
@@ -385,10 +385,9 @@ describe("shouldDeleteAgentConfig", () => {
 
   test("returns true when all fields match category defaults", () => {
     // #given: Config with fields matching category defaults
-    // Note: DEFAULT_CATEGORIES only has temperature, not model
     const config = {
       category: "visual-engineering",
-      temperature: 0.7,
+      model: "google/gemini-3-pro-preview",
     }
 
     // #when: Check if config should be deleted
@@ -399,10 +398,10 @@ describe("shouldDeleteAgentConfig", () => {
   })
 
   test("returns false when fields differ from category defaults", () => {
-    // #given: Config with custom temperature override
+    // #given: Config with custom model override
     const config = {
       category: "visual-engineering",
-      temperature: 0.9, // Different from default (0.7)
+      model: "anthropic/claude-opus-4-5",
     }
 
     // #when: Check if config should be deleted
@@ -415,10 +414,10 @@ describe("shouldDeleteAgentConfig", () => {
   test("handles different categories with their defaults", () => {
     // #given: Configs for different categories
     const configs = [
-      { category: "ultrabrain", temperature: 0.1 },
-      { category: "quick", temperature: 0.3 },
-      { category: "most-capable", temperature: 0.1 },
-      { category: "general", temperature: 0.3 },
+      { category: "ultrabrain" },
+      { category: "quick" },
+      { category: "unspecified-high" },
+      { category: "unspecified-low" },
     ]
 
     // #when: Check each config