Notify question authors via Resend when an admin posts the first answer.

Require email at registration (editable on profile), add a Resend mailer with idempotent first-answer sends, and keep answer saves independent of delivery.

db/queries/users.sql

@@ -1,24 +1,25 @@
 -- name: CreateUser :exec
-INSERT INTO users (id, username, name, password_hash, role, avatar_url, state, created_at)
-VALUES ($1, $2, $3, $4, $5, '', '', $6);
+INSERT INTO users (id, username, name, password_hash, role, email, avatar_url, state, created_at)
+VALUES ($1, $2, $3, $4, $5, $6, '', '', $7);
 
 -- name: GetUserByID :one
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE id = $1;
 
 -- name: GetUserByUsername :one
-SELECT id, username, name, role, avatar_url, state, created_at, password_hash
+SELECT id, username, name, role, email, avatar_url, state, created_at, password_hash
 FROM users
 WHERE username = $1;
 
 -- name: ListUsers :many
-SELECT id, username, name, role, avatar_url, state, created_at
+SELECT id, username, name, role, email, avatar_url, state, created_at
 FROM users
 WHERE (
   sqlc.arg(search) = ''
   OR username ILIKE '%' || sqlc.arg(search) || '%'
   OR name ILIKE '%' || sqlc.arg(search) || '%'
+  OR email ILIKE '%' || sqlc.arg(search) || '%'
 )
 AND (
   sqlc.arg(cursor_created) = ''
@@ -43,12 +44,12 @@ UPDATE users
 SET role = $1
 WHERE id = $2;
 
--- name: UpdateUserState :exec
+-- name: UpdateUserProfile :exec
 UPDATE users
-SET state = $1
-WHERE id = $2;
-
--- name: UpdateUserStateAndAvatar :exec
-UPDATE users
-SET state = $1, avatar_url = $2
+SET state = $1, email = $2
 WHERE id = $3;
+
+-- name: UpdateUserProfileAndAvatar :exec
+UPDATE users
+SET state = $1, email = $2, avatar_url = $3
+WHERE id = $4;