fix(#411): QA-010 — fix minor JSDoc and comment issues across auth files

Fix response.ok JSDoc (2xx not 200), remove stale token refresh claim,
remove non-actionable comment, fix CSRF comment placement, add 403 mapping rationale.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/auth/auth.controller.ts

@@ -112,12 +112,9 @@ export class AuthController {
    * Rate limiting and logging are applied to mitigate abuse (SEC-API-10).
    */
   @All("*")
-  /**
-   * BetterAuth implements CSRF protection internally via Fetch Metadata headers
-   * (Sec-Fetch-Site, Sec-Fetch-Mode) and SameSite=Lax cookies. The @SkipCsrf()
-   * decorator skips the custom CSRF guard to avoid double-protection conflicts.
-   * Reference: https://www.better-auth.com/docs/reference/security
-   */
+  // BetterAuth handles CSRF internally (Fetch Metadata + SameSite=Lax cookies).
+  // @SkipCsrf avoids double-protection conflicts.
+  // See: https://www.better-auth.com/docs/reference/security
   @SkipCsrf()
   @Throttle({ strict: { limit: 10, ttl: 60000 } })
   async handleAuth(@Req() req: ExpressRequest, @Res() res: ExpressResponse): Promise<void> {