Fix: Stop repeated context-window notices when restoring sessions

[DevMando]

Problem

Reopening a saved conversation could display the same “Context window sized to 16k tokens” message multiple times. Restoring the saved model generated another setup notice, while notices from earlier sessions were replayed from the saved transcript. This made normal session recovery look like repeated configuration changes.

What changes

• Restoring a saved model no longer adds context-sizing or cloud-subscription reminders.
• Previously saved copies of these setup notices are hidden when the conversation is restored, so existing sessions benefit without clearing their history.
• Manual model changes still show relevant notices. Conversation messages, quoted text, and actual warnings remain visible.

The model's context window is still configured normally; this fix changes the messaging, not model behavior.

Validation

• Desktop build passed with zero warnings and errors, using a separate output folder to avoid the running app's file locks.
• Both focused regression tests passed, covering repeated historical notices and preservation of conversation text and warnings.
• Full manual session-restoration walkthrough has not been performed for this change.