Add authentication system with session-based auth

Implements full auth flows with opaque tokens (not JWT) for easy revocation:
- Login/logout with cookie or bearer token support
- Registration with email verification
- Password reset with one-time tokens
- scrypt password hashing (no external deps)

New files in express/auth/:
- token.ts: 256-bit token generation, SHA-256 hashing
- password.ts: scrypt hashing with timing-safe verification
- types.ts: Session schemas, token types, input validation
- store.ts: AuthStore interface + InMemoryAuthStore
- service.ts: AuthService with all auth operations
- routes.ts: 6 auth endpoints

Modified:
- types.ts: Added user field to Call, requireAuth/requirePermission helpers
- app.ts: JSON body parsing, populates call.user, handles auth errors
- services.ts: Added services.auth
- routes.ts: Includes auth routes

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

express/auth/password.ts

@@ -0,0 +1,67 @@
+// password.ts
+//
+// Password hashing using Node.js scrypt (no external dependencies).
+// Format: $scrypt$N$r$p$salt$hash (all base64)
+
+import {
+    randomBytes,
+    type ScryptOptions,
+    scrypt,
+    timingSafeEqual,
+} from "node:crypto";
+
+// Configuration
+const SALT_LENGTH = 32;
+const KEY_LENGTH = 64;
+const SCRYPT_PARAMS: ScryptOptions = {
+    N: 16384, // CPU/memory cost parameter (2^14)
+    r: 8, // Block size
+    p: 1, // Parallelization
+};
+
+// Promisified scrypt with options support
+function scryptAsync(
+    password: string,
+    salt: Buffer,
+    keylen: number,
+    options: ScryptOptions,
+): Promise<Buffer> {
+    return new Promise((resolve, reject) => {
+        scrypt(password, salt, keylen, options, (err, derivedKey) => {
+            if (err) reject(err);
+            else resolve(derivedKey);
+        });
+    });
+}
+
+async function hashPassword(password: string): Promise<string> {
+    const salt = randomBytes(SALT_LENGTH);
+    const hash = await scryptAsync(password, salt, KEY_LENGTH, SCRYPT_PARAMS);
+
+    const { N, r, p } = SCRYPT_PARAMS;
+    return `$scrypt$${N}$${r}$${p}$${salt.toString("base64")}$${hash.toString("base64")}`;
+}
+
+async function verifyPassword(
+    password: string,
+    stored: string,
+): Promise<boolean> {
+    const parts = stored.split("$");
+    if (parts[1] !== "scrypt" || parts.length !== 7) {
+        throw new Error("Invalid password hash format");
+    }
+
+    const [, , nStr, rStr, pStr, saltB64, hashB64] = parts;
+    const salt = Buffer.from(saltB64, "base64");
+    const storedHash = Buffer.from(hashB64, "base64");
+
+    const computedHash = await scryptAsync(password, salt, storedHash.length, {
+        N: parseInt(nStr, 10),
+        r: parseInt(rStr, 10),
+        p: parseInt(pStr, 10),
+    });
+
+    return timingSafeEqual(storedHash, computedHash);
+}
+
+export { hashPassword, verifyPassword };