Custom Signatures + Admin Mailbox Controls

🔹 Custom Signatures Per Mailbox
Add unique email signatures for each connected mailbox — perfect for multi-brand setups.

🔹 Admin Mailbox Controls
Admins can now update mailbox-level settings (Send As name, signature, and more) directly inside Snoooz.

🔹 GPT-5 Rollout Paused
We rolled back the GPT-5 test due to quality inconsistencies. Fine-tuning continues — quality first.

🔹 Bug Fixes & UI Improvements
Reliable SMTP/IMAP validation, safer rule editing, easier navigation, better error prevention, and cleaner layouts.