feat(tabs): keep alerted tabs visible during a rail search

A session with a tab alert (red action or yellow idle, whatever tabAlerts
holds, the same set a collapsed group header surfaces) now stays visible
while the rail search or the sidebar filter is narrowing the list, even
when its name does not match. A prompt waiting on you should never be
hidden by a view filter.

The pure CodemanTabSearch.filter decides it: a row passed with keep: true
is never hidden. It counts toward its group, so the group stays on screen
and the header number is the rows left showing, but not toward
matchCount, so "No sessions match" still shows above a lone alerted row.
_applyTabListFilter() flags session rows from tabAlerts; web tabs carry
no alerts and are never kept.

No new wiring: updateTabAlertFromHooks() and _onSessionWorking() already
call renderSessionTabs(), and both render paths end in the shared filter.

docs/wiki/The-Dashboard.md

@@ -29,7 +29,7 @@ Session List Layout** can move it into a vertical sidebar on the left instead, a
 | -------------------- | --------------------------------------------------------------------------------- |
 | **Header tab strip** | The default. One list in tab order unless you pick another [Tab layout](#tab-layouts); it scrolls sideways on a phone. |
 | **Left sidebar**     | A vertical list with a filter box and a live session count. `Alt+B` collapses it to a narrow rail that keeps the status dots and task badges visible. On a phone it is an off-canvas drawer rather than a docked rail. A detailed variant adds the home screen's per-session line (`created 3d ago · working 12m`) and a status pill. |
-| **Vertical rail**    | The strip turned vertical beside the terminal, resizable, with detailed rows by default. **Vertical Rail Order** sorts it by activity (blocked on you first, then longest running, then most recently quiet), the same order as the home screens; pick *Manual* to get your own order and drag-reordering back. **Tab groups:** pick *Move to new group* from a row's ⋯ menu (or Shift+F10 on it) to make the first one; a group header's menu (right-click, Shift+F10 or its ⋯ glyph) renames it (also F2), reorders or deletes it, rows move between groups from their own menu or by dragging with a mouse or pen, and a collapsed group stays collapsed on that device. **Search sessions** at the top of the rail narrows it to the tabs whose name matches (a web tab by its title), across every group, collapsed ones included, without changing the groups or the order; Escape or × clears it, and it is never saved. Desktop and tablet only. |
+| **Vertical rail**    | The strip turned vertical beside the terminal, resizable, with detailed rows by default. **Vertical Rail Order** sorts it by activity (blocked on you first, then longest running, then most recently quiet), the same order as the home screens; pick *Manual* to get your own order and drag-reordering back. **Tab groups:** pick *Move to new group* from a row's ⋯ menu (or Shift+F10 on it) to make the first one; a group header's menu (right-click, Shift+F10 or its ⋯ glyph) renames it (also F2), reorders or deletes it, rows move between groups from their own menu or by dragging with a mouse or pen, and a collapsed group stays collapsed on that device. **Search sessions** at the top of the rail narrows it to the tabs whose name matches (a web tab by its title), across every group, collapsed ones included, without changing the groups or the order; a tab with an alert stays visible even when its name does not match; Escape or × clears it, and it is never saved. Desktop and tablet only. |
 
 It is the same list either way, just re-hosted: tab order, drag-to-reorder, the `Alt+1`
 to `Alt+9` numbers and every status colour below behave identically in both. The setting is