feat(tabs): Tab Layout setting with by case (A) and ledger (B), reversible state order, cleaner tiles (#426)

Tab Grouping becomes Tab Layout (tabArrangement: 'state' | 'case' |
'ledger' | 'classic', default 'state'), the first row of App Settings,
Appearance, Tabs, so the old and the new strip are one choice apart.

- By case (option A): each case's tabs sit in one .tab-cluster box in
  first-appearance order, labelled with the case and its count, coloured
  by a stable hash into the session palette. Membership is
  _mobileOverviewCaseFor(), the home screens' own match. Inside a box with
  company a generated w75-api-gateway reads w75; the -<case> stays in the
  DOM in a .tab-name-case span only .tabs-clusters hides. The incremental
  render path rebuilds only when the cluster structure key changes. The
  rail and the sidebar get a labelled section per case; phones dissolve
  the boxes into the chip row. Drag stays inside one box.
- Ledger (option B): CSS only on .tabs-ledger, desktop header strip: an
  auto-fill column grid of equal cells in mono type with a 3px status
  bar. Its markup is identical to classic's.
- State Order (tabStateOrder: 'urgent-first' | 'urgent-last'): flips the
  by-state groups so needs you can be the bottom row.
- By state: the label column is measured to the widest label on screen
  and the labels are right-aligned in it, instead of a fixed 92px gutter
  that left short labels far from their tabs.
- Tiles: a three-row grid (label, value, bar) with pixel line-heights in
  the bundled JetBrains Mono, 36px like the header. The bar used to lie
  over a fixed 28px tile, and a taller system mono (SF Mono) pushed the
  value into it. The WS tile's grid moved onto an inner .connection-tile
  span because JS writes the indicator's display inline. Compact uses the
  same font and a matched WS size.

Tests: test/tab-clusters.test.ts (new), plus the rename and the reversed
order in test/tab-triage.test.ts.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/wiki/Settings-Reference.md

@@ -89,8 +89,9 @@ every session or only the active tab.
 | Interface Language     | English or Simplified Chinese. Per device.                                                 |
 | Session List Layout    | Header tab strip (default), a collapsible left sidebar, or the sidebar with detailed rows. See [The Dashboard](The-Dashboard#session-list-layout). |
 | Tab Orientation        | Keeps the header list but turns the strip vertical beside the terminal, resizable, with detailed rows by default. Desktop and tablet only. |
-| Tab Grouping           | *By state* (default) splits the tabs into needs you, waiting, working and idle: rows in the header, sections in the rail and sidebar. *None* keeps one list in tab order. See [The Dashboard](The-Dashboard#tab-grouping-by-state). |
-| Vertical Rail Order    | *By activity* (default) sorts the rail the way the home screens are sorted; *Manual* keeps your tab order and drag-reordering. With grouping by state it orders the rows inside each section. |
+| Tab Layout             | *By state* (default): a row each for needs you, waiting, working and idle, sections in the rail and sidebar. *By case*: one box per case. *Ledger*: an aligned column grid. *Classic*: the single list as before. See [The Dashboard](The-Dashboard#tab-layouts). |
+| State Order            | For *By state*: needs you on top (default) or at the bottom, right above the terminal. |
+| Vertical Rail Order    | *By activity* (default) sorts the rail the way the home screens are sorted; *Manual* keeps your tab order and drag-reordering. With *By state* or *By case* it orders the rows inside each section. |
 | Tall Tabs              | Taller tab strip.                                                                          |
 | Pop-out Button on Tabs | Adds the detach control to tabs, with a per-tab override.                                  |
 | Spawn Lineage Lines    | Arcs from a parent tab to sessions it spawned. Desktop only, on by default.                |