feat(04-01): update thread service, routes, and hooks for categoryId

- createThread now inserts categoryId from data
- getAllThreads joins categories table, returns categoryName/categoryEmoji
- updateThread accepts optional categoryId
- ThreadListItem interface includes category fields
- useCreateThread hook sends categoryId
- Fix test files to pass categoryId when creating threads

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/routes/threads.test.ts

@@ -17,11 +17,11 @@ function createTestApp() {
   return { app, db };
 }
 
-async function createThreadViaAPI(app: Hono, name: string) {
+async function createThreadViaAPI(app: Hono, name: string, categoryId = 1) {
   const res = await app.request("/api/threads", {
     method: "POST",
     headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ name }),
+    body: JSON.stringify({ name, categoryId }),
   });
   return res.json();
 }
@@ -48,7 +48,7 @@ describe("Thread Routes", () => {
       const res = await app.request("/api/threads", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ name: "New Tent" }),
+        body: JSON.stringify({ name: "New Tent", categoryId: 1 }),
       });
 
       expect(res.status).toBe(201);