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>

app/(api)/auth/register+api.ts

@@ -14,7 +14,7 @@ const hashCode = (email: string, code: string): string =>
   createHash("sha256").update(`${email}:${code}`).digest("hex");
 
 export async function POST(req: Request) {
-  const { name, email, phone, password } = await req.json();
+  const { name, email, phone, password, role } = await req.json();
 
   if (!name?.trim() || !email?.trim() || !password) {
     return Response.json(
@@ -23,6 +23,8 @@ export async function POST(req: Request) {
     );
   }
 
+  const normalizedRole = role === "driver" ? "driver" : "rider";
+
   if (typeof password !== "string" || password.length < 8) {
     return Response.json(
       { error: "Password must be at least 8 characters." },
@@ -44,18 +46,20 @@ export async function POST(req: Request) {
 
     // Unverified rows may be re-registered (e.g. the first mail never arrived).
     await sql`
-      INSERT INTO users (name, email, phone, password_hash, email_verified)
+      INSERT INTO users (name, email, phone, password_hash, email_verified, role)
       VALUES (
         ${name.trim()},
         ${email.trim().toLowerCase()},
         ${phone ? normalizePhone(phone) : null},
         ${hashPassword(password)},
-        FALSE
+        FALSE,
+        ${normalizedRole}
       )
       ON CONFLICT (email) DO UPDATE SET
         name = EXCLUDED.name,
         phone = COALESCE(EXCLUDED.phone, users.phone),
-        password_hash = EXCLUDED.password_hash
+        password_hash = EXCLUDED.password_hash,
+        role = EXCLUDED.role
     `;
 
     const code = String(randomInt(0, 1_000_000)).padStart(6, "0");
@@ -73,13 +77,23 @@ export async function POST(req: Request) {
         attempts = 0
     `;
 
-    await sendEmail(
+    const delivered = await sendEmail(
       email.trim().toLowerCase(),
       "Your Waseel verification code",
       `Welcome to Waseel!\n\nYour verification code is: ${code}\n\nIt expires in 15 minutes.`,
     );
 
-    return Response.json({ data: { sent: true } }, { status: 201 });
+    return Response.json(
+      {
+        data: {
+          sent: delivered,
+          // Without SMTP/Gmail configured there is nothing to receive, so
+          // surface the code to keep self-hosted sign-up usable.
+          ...(delivered ? {} : { devCode: code }),
+        },
+      },
+      { status: 201 },
+    );
   } catch (error) {
     console.error("[REGISTER]: ", error);
     return Response.json({ error: "Internal Server Error" }, { status: 500 });