[Bug][Mobile] Archive action is missing from thread actions

Description

The iOS mobile thread list does not provide an Archive action. The long-press menu includes Settle, Snooze, Pin, Regenerate title, and Delete, but no Archive. The swipe actions expose only Settle and Snooze.

This prevents mobile users from removing an old thread from the active list while preserving the conversation.

Actual behavior

• The long-press thread menu has no Archive action.
• The swipe actions have no Archive action.
• Delete is the only visible action that removes the thread from the active list, but Delete is destructive.
• Settle is not an equivalent replacement because it leaves the thread in the settled area and uses different thread lifecycle behavior.

Expected behavior

• Add an Archive action to the mobile thread menu.
• Add Archive as a swipe action if that is the intended mobile interaction.
• After a successful archive, remove the thread from the active list.
• Preserve the conversation in the Archived threads view.
• Keep Archive separate from Settle and Delete.
• Show success or error feedback when the archive command completes.

Steps to reproduce

1. Open T3 Code on an iOS device.
2. Open a project with at least one thread.
3. Long-press a thread.
4. Inspect the available actions.
5. Confirm that Archive is missing.
6. Swipe the same thread row.
7. Confirm that only Settle and Snooze are available.

Screenshots

The attached mobile screenshots show:

• The long-press menu with Settle, Snooze, Pin, Regenerate title, and Delete.
• The swipe actions with Settle and Snooze.
• No Archive action in either interaction.

Environment

• Device: iPhone
• App: T3 Code mobile
• App version/build: not visible in the screenshots
• Server or nightly build: not captured

Acceptance criteria

• A mobile user can archive a thread without deleting it.
• An archived thread disappears from the active list.
• The conversation remains available in Archived threads.
• Existing Settle, Snooze, Pin, and Delete behavior does not regress.
• The archive action reports command failure instead of silently leaving the thread unchanged.

Related reports and changes

• Mobile: make thread archiving one-swipe and recoverable (#5204)
• Archive action is missing from the default sidebar thread menu (#6511)
• fix(web): restore the Archive action in the default sidebar thread menu (#6526)
• Add swipe-to-archive on mobile thread list (#2045)

This report is specifically about the current iOS mobile experience. Please treat it as a current mobile parity gap or regression if the linked work was intended to cover this path.

Start by locating the iOS mobile thread list and its long-press and swipe action entry points. Trace the existing Settle, Snooze, and Delete behavior before adding the corresponding Archive path. Done means Archive is available without replacing those actions, removes the thread from the active list, preserves it in Archived threads, and reports success or failure.