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/token.ts

@@ -0,0 +1,40 @@
+// token.ts
+//
+// Token generation and hashing utilities for authentication.
+// Raw tokens are never stored - only their SHA-256 hashes.
+
+import { createHash, randomBytes } from "node:crypto";
+
+const TOKEN_BYTES = 32; // 256 bits of entropy
+
+// Generate a cryptographically secure random token
+function generateToken(): string {
+    return randomBytes(TOKEN_BYTES).toString("base64url");
+}
+
+// Hash token for storage (never store raw tokens)
+function hashToken(token: string): string {
+    return createHash("sha256").update(token).digest("hex");
+}
+
+// Parse token from Authorization header
+function parseAuthorizationHeader(header: string | undefined): string | null {
+    if (!header) return null;
+
+    const parts = header.split(" ");
+    if (parts.length !== 2 || parts[0].toLowerCase() !== "bearer") {
+        return null;
+    }
+
+    return parts[1];
+}
+
+// Cookie name for web sessions
+const SESSION_COOKIE_NAME = "diachron_session";
+
+export {
+    generateToken,
+    hashToken,
+    parseAuthorizationHeader,
+    SESSION_COOKIE_NAME,
+};