v2.7.7

Fix aggressive rate limiting that was locking out legitimate users

Rate limit changes:

• General: 120 → 500 req/min
• Auth: 30 → 100 req/min (page loads + attempts)
• Auth POST: new 20 req/min limit (form submissions only)
• Localhost: rate limiting skipped entirely (Electron app)
• Better error messages with retry-after info