add backend auth

backend/internal/db/queries/auth.sql

@@ -0,0 +1,25 @@
+-- name: CreateUser :one
+INSERT INTO users (username, password_hash)
+VALUES ($1, $2)
+RETURNING *;
+
+-- name: GetUserByUsername :one
+SELECT * FROM users WHERE username = $1;
+
+-- name: GetUserByID :one
+SELECT * FROM users WHERE id = $1;
+
+-- name: CreateRefreshToken :one
+INSERT INTO refresh_tokens (user_id, token_hash, expires_at)
+VALUES ($1, $2, $3)
+RETURNING *;
+
+-- name: GetRefreshToken :one
+SELECT * FROM refresh_tokens
+WHERE token_hash = $1 AND revoked = FALSE AND expires_at > NOW();
+
+-- name: RevokeRefreshToken :exec
+UPDATE refresh_tokens SET revoked = TRUE WHERE token_hash = $1;
+
+-- name: RevokeAllUserRefreshTokens :exec
+UPDATE refresh_tokens SET revoked = TRUE WHERE user_id = $1;