feat(02-01): add thread API routes and mount in server

- Thread CRUD: GET /, POST /, GET /:id, PUT /:id, DELETE /:id
- Candidate CRUD: POST /:id/candidates, PUT/DELETE nested candidates
- Resolution: POST /:id/resolve with validation and error handling
- Image cleanup on thread/candidate deletion
- Routes mounted at /api/threads in server index

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

src/server/index.ts

@@ -6,6 +6,7 @@ import { categoryRoutes } from "./routes/categories.ts";
 import { totalRoutes } from "./routes/totals.ts";
 import { imageRoutes } from "./routes/images.ts";
 import { settingsRoutes } from "./routes/settings.ts";
+import { threadRoutes } from "./routes/threads.ts";
 
 // Seed default data on startup
 seedDefaults();
@@ -23,6 +24,7 @@ app.route("/api/categories", categoryRoutes);
 app.route("/api/totals", totalRoutes);
 app.route("/api/images", imageRoutes);
 app.route("/api/settings", settingsRoutes);
+app.route("/api/threads", threadRoutes);
 
 // Serve uploaded images
 app.use("/uploads/*", serveStatic({ root: "./" }));