Mobile: swipe from the Home thread list to a projects view

[Pivii]

Where: mobile app (iOS), Home thread list.

Problem. On the Home thread list, the only way to switch or browse projects is the project filter in the bottom-left corner. It takes a tap, a menu, and another tap. When I check on agents from my phone I often want to jump between projects quickly, and the filter feels like a detour, whether the list is currently filtered to one project or showing all of them.

Proposal. From the Home thread list (not from inside a chat), a swipe left (edge swipe or horizontal pan) reveals a projects view: the list of projects/folders, each opening the thread list filtered to that project. Swiping back returns to the thread list with the previous filter state.

This works the same whether the thread list is filtered or showing all projects. The bottom-left filter stays as-is for discoverability; the swipe is a faster path to the same place.

Why it matters on a phone: one gesture instead of three taps for the most common navigation on Home, and a place where the project structure is visible at a glance.

Open questions:

• Should the projects view show per-project status (working / input needed / done counts)? That would make it a quick overview of where attention is needed.
• Conflict with the iOS back-swipe gesture: this is only proposed on Home, which has no back destination.

Related: #13141 (group the thread list by project), #13666 (mobile project filters reset across layout changes).