chore: update GPT-5.2 references to GPT-5.4

Align runtime defaults, tests, docs, and generated artifacts with the newer GPT-5.4 baseline. Keep think-mode and prompt-routing expectations consistent after the model version bump.

src/shared/merge-categories.test.ts

@@ -44,7 +44,7 @@ describe("mergeCategories", () => {
   it("allows user to add custom categories", () => {
     //#given
     const userCategories = {
-      "my-custom": { model: "openai/gpt-5.2", description: "Custom category" },
+      "my-custom": { model: "openai/gpt-5.4", description: "Custom category" },
     }
 
     //#when
@@ -52,13 +52,13 @@ describe("mergeCategories", () => {
 
     //#then
     expect(result["my-custom"]).toBeDefined()
-    expect(result["my-custom"].model).toBe("openai/gpt-5.2")
+    expect(result["my-custom"].model).toBe("openai/gpt-5.4")
   })
 
   it("allows user to disable custom categories", () => {
     //#given
     const userCategories = {
-      "my-custom": { model: "openai/gpt-5.2", disable: true },
+      "my-custom": { model: "openai/gpt-5.4", disable: true },
     }
 
     //#when