Alt+Tab window switcher (MRU), snap/maximize, panel separators

- window_switcher action: overlay listing windows in most-recently-used
  order; Tab/arrows cycle, Enter confirms, Esc cancels. Bound to
  alt+tab with alt+w as fallback for terminals that swallow alt+tab
- snap_left/snap_right actions (alt+left/alt+right) tile the focused
  window to half the content area; dragging a window to the screen
  edge snaps it too
- maximize action (alt+up) toggles maximize/restore, double-click on
  the title bar does the same; restore returns the pre-snap geometry
- Panel: separator between focus dot and buttons, separators between
  right-docked status widgets, and item widths now use display width
  (fixes rects for åäö/wide labels)
- Integration suite: 23 checks, all passing

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/integration.py

@@ -274,6 +274,38 @@ def main():
         if top_win:
             app.send({"type": "close_window", "window_id": top_win["id"]})
 
+        # ── 4e. Alt+Tab-växlare + snap/maximera ──────────────────────────
+        # Två fönster finns (mouse-test + top stängdes; spawna ett till)
+        app.send({"type": "spawn_window", "command": "exec cat",
+                  "request_id": "w-sw"})
+        sw_open = app.recv_until("window_opened")
+        disp.send(key_event(code="Tab", modifiers="ALT"))
+        text = disp.frame_text(timeout=5.0, contains="Fönster")
+        check("alt+tab öppnar fönsterväxlaren", "Fönster" in text)
+        disp.send(key_event(code="Esc"))
+        time.sleep(0.2)
+
+        # Snap vänster: fokuserat fönster ska bli halva bredden
+        disp.send(key_event(code="Left", modifiers="ALT"))
+        time.sleep(0.3)
+        app.send({"type": "list_windows", "request_id": "lsnap"})
+        wsn = app.recv_until("window_list")
+        snapped = next(w for w in wsn["windows"] if w["id"] == sw_open["id"])
+        # innehållsytan är 100 bred (minus panel högst upp) → halvan ~50
+        check("alt+left fäster fönstret som halvskärm",
+              45 <= snapped["width"] <= 55 and snapped["x"] <= 1,
+              f"geometri: {snapped}")
+
+        # Maximera/återställ: alt+up två gånger ska ge tillbaka snappad storlek
+        disp.send(key_event(code="Up", modifiers="ALT"))
+        time.sleep(0.3)
+        app.send({"type": "list_windows", "request_id": "lmax"})
+        wmx = app.recv_until("window_list")
+        maxed = next(w for w in wmx["windows"] if w["id"] == sw_open["id"])
+        check("alt+up maximerar fönstret", maxed["width"] >= 95,
+              f"geometri: {maxed}")
+        app.send({"type": "close_window", "window_id": sw_open["id"]})
+
         # ── 5. Popup + popup_result via Enter ───────────────────────────
         app.send({
             "type": "spawn_popup", "message": "Integrationstest?",