fix(kitty): restore per-host tab colors in the custom tab bar

a68b138 made draw_tab() derive all four color roles from tab_colors(),
so it stopped reading the per-tab colors that `kitten @ set-tab-color`
sets. The ssh wrapper (__kitty_tab_set) still set them, but the renderer
discarded them and every remote tab drew in the #2e84e6 accent.

Resolve the drawn colors through DrawData.tab_fg/tab_bg on the already
role-substituted title_draw_data: those return the per-tab override when
one is set and the accent roles otherwise. Theme-provided tab colors
still cannot leak in, so the theme-independence fix is preserved.

Extend tests/test_tab_bar_colors.py with the override case; it fails
against the old renderer (got the accent, wanted the host color).

private_dot_config/kitty/private_tests/private_test_tab_bar_colors.py

@@ -87,7 +87,37 @@ for theme_bg in (0xF8F8F8, 0x1C2836):
                 f"got {(actual_fg, actual_bg)!r}"
             )
 
+# Per-tab colors set by `kitten @ set-tab-color` (see fish __kitty_tab_set)
+# must win over the accent, or ssh tabs all render in the same blue.
+HOST_BG = 0x689D6A
+HOST_FG = 0x000000
+
+for theme_bg in (0xF8F8F8, 0x1C2836):
+    for tab, expected, label in (
+        (
+            TabBarData("tab", is_active=True, active_bg=HOST_BG, active_fg=HOST_FG),
+            (as_rgb(HOST_FG), as_rgb(HOST_BG)),
+            "active tab takes the host color",
+        ),
+        (
+            TabBarData("tab", is_active=False, inactive_fg=HOST_BG),
+            (as_rgb(HOST_BG), as_rgb(theme_bg)),
+            "inactive tab keeps the theme background, host color as text",
+        ),
+    ):
+        screen = RecordingScreen()
+        renderer.draw_tab(
+            draw_data(theme_bg), screen, tab, 0, 1, 1, True, ExtraData()
+        )
+        _, actual_fg, actual_bg = screen.draws[0]
+        if (actual_fg, actual_bg) != expected:
+            raise RuntimeError(
+                f"theme #{theme_bg:06x}, {label}: "
+                f"expected cursor colors {expected!r}, "
+                f"got {(actual_fg, actual_bg)!r}"
+            )
+
 print(
     "PASS: tab colors ignore theme-provided tab roles "
-    "for light and dark backgrounds"
+    "for light and dark backgrounds, and honor per-tab set-tab-color overrides"
 )

private_dot_config/kitty/tab_bar.py

@@ -24,12 +24,12 @@ def draw_tab(
     extra_data: ExtraData
 ) -> int:
     colors = tab_colors(draw_data.default_bg)
-    fg = colors.active_fg if tab.is_active else colors.inactive_fg
-    bg = colors.active_bg if tab.is_active else colors.inactive_bg
-    default_bg = as_rgb(int(draw_data.default_bg))
-    orig_fg = as_rgb(int(fg))
-    orig_bg = as_rgb(int(bg))
     title_draw_data = draw_data._replace(**colors._asdict())
+    default_bg = as_rgb(int(draw_data.default_bg))
+    # tab_fg/tab_bg return a per-tab color when `kitten @ set-tab-color` has set
+    # one (the ssh wrapper tints tabs per host), else the roles above.
+    orig_fg = as_rgb(title_draw_data.tab_fg(tab))
+    orig_bg = as_rgb(title_draw_data.tab_bg(tab))
     screen.cursor.fg = orig_fg
     screen.cursor.bg = orig_bg
     left_sep, right_sep = ('', '')