fix: kitty status bar clock — redraw via add_timer, drop bogus tab_bar_timeout

kitty has no tab_bar_timeout option (ignored with a warning), so the clock/CPU/mem
only refreshed on tab changes. tab_bar.py now registers a repeating 10s timer that
marks every tab bar dirty. Verified in Xvfb: idle window's clock ticked 16:21 -> 16:22.

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

kitty/tab_bar.py

@@ -9,6 +9,7 @@ import os
 import subprocess
 from datetime import datetime
 
+from kitty.fast_data_types import add_timer, get_boss
 from kitty.tab_bar import (
     DrawData,
     ExtraData,
@@ -36,6 +37,16 @@ _DIM = as_rgb(0x666666)
 _TAB_BG = as_rgb(0x1A1A1A)
 _BAR_BG = as_rgb(0x0D0D0D)
 
+# kitty only redraws the tab bar on tab changes; this timer keeps the clock/stats live.
+# ponytail: 10s = clock lags <=10s; each redraw runs git on kitty's main thread, so don't go much lower.
+REFRESH_SECS = 10.0
+_timer_id = None
+
+
+def _refresh(_timer_id) -> None:
+    for tm in get_boss().all_tab_managers:
+        tm.mark_tab_bar_dirty()
+
 
 def _get_git_branch() -> str:
     try:
@@ -106,6 +117,10 @@ def draw_tab(
     is_last: bool,
     extra_data: ExtraData,
 ) -> int:
+    global _timer_id
+    if _timer_id is None:
+        _timer_id = add_timer(_refresh, REFRESH_SECS, True)
+
     # Build tab title
     title = tab.title
     if _prefix: