feat(auth): add user registration endpoint

Implement POST /api/auth/register endpoint with:
- Argon2 password hashing
- Zod validation for username (1-255 chars) and password (8-255 chars)
- Duplicate username check (returns 409 Conflict)
- Returns created user with id, username, and createdAt

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/pkgs/server/src/index.ts b/pkgs/server/src/index.ts
index a00c9fd..a0ae0a4 100644
--- a/pkgs/server/src/index.ts
+++ b/pkgs/server/src/index.ts
@@ -2,6 +2,7 @@ import { serve } from "@hono/node-server";
 import { Hono } from "hono";
 import { logger } from "hono/logger";
 import { errorHandler } from "./middleware";
+import { auth } from "./routes";
 
 const app = new Hono();
 
@@ -16,6 +17,8 @@ app.get("/api/health", (c) => {
 	return c.json({ status: "ok" });
 });
 
+app.route("/api/auth", auth);
+
 const port = Number(process.env.PORT) || 3000;
 console.log(`Server is running on port ${port}`);