Implement auth procedures with code review fixes

Add complete auth backend (Workstream D):
- Auth middleware for session/API key authentication
- Signup with password or passkey (WebAuthn)
- Login flow with device trust and email confirmation
- Password reset and email verification
- Session management and logout

Utilities created:
- cookies.ts: Cookie helpers and configuration
- crypto.ts: Token generation and hashing
- password.ts: zxcvbn validation, argon2id hashing
- geo.ts: IP/location extraction from headers
- email.ts: Stubbed email sending
- session.ts: Session creation and device trust

Code review improvements applied:
- Use ORPCError instead of Error in procedures
- Add ast-grep rule to enforce ORPCError usage
- Remove error info leakage (generic messages)
- Optimize N+1 query with JOIN in login-password
- Extract signupWithPassword/signupWithPasskey for testability
- Add 15-minute WebAuthn challenge expiry check
- Strengthen CookieOptions type definitions

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

apps/api-server/src/context.ts

@@ -17,6 +17,10 @@ export interface APIContext {
   allowedOrigins: string[];
   /** Relying party name for WebAuthn */
   rpName: string;
+  /** Request headers (for reading cookies, auth headers) */
+  reqHeaders: Headers;
+  /** Response headers (for setting cookies) */
+  resHeaders: Headers;
 }
 
 /**