Fix SMTP delivery, add password reset and user deletion

SMTP:
- Add connection/greeting/socket timeouts so a stalled Gmail
  connection no longer hangs sign-up
- Wrap sendMail in try/catch and fall back to logging the code
- Derive secure from port (465 implicit TLS vs 587 STARTTLS)
- Strip whitespace from the Gmail app password
- Document SMTP_HOST/SMTP_PORT in .env.example and environment.d.ts

Password reset (new):
- POST /(api)/auth/forgot-password emails a 6-digit code and does
  not reveal whether the address is registered
- POST /(api)/auth/reset-password validates the code, sets the new
  password, verifies the email, and signs the user in
- password_reset_codes table added to seed-db.mjs
- "Forgot password?" flow on the mobile sign-in screen

User deletion (new):
- DELETE /(api)/admin/users/[id], owner-only, blocks self-deletion
- Delete button with confirmation on the dashboard Users page

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/seed-db.mjs

@@ -92,6 +92,13 @@ await sql`CREATE TABLE IF NOT EXISTS email_verification_codes (
   expires_at TIMESTAMP NOT NULL
 )`;
 
+await sql`CREATE TABLE IF NOT EXISTS password_reset_codes (
+  email VARCHAR(255) PRIMARY KEY,
+  code_hash TEXT NOT NULL,
+  attempts INTEGER NOT NULL DEFAULT 0,
+  expires_at TIMESTAMP NOT NULL
+)`;
+
 await sql`CREATE TABLE IF NOT EXISTS drivers (
   id SERIAL PRIMARY KEY,
   first_name VARCHAR(100) NOT NULL,