fix(web): dark-mode tokens for popup primitives + theme-color/color-scheme sync (#68)

Tooltip, toast, and combobox popups still hardcoded light colors
(bg-white, neutral-*, indigo-50) and rendered as white boxes in dark
mode; the objects-table page-size select did the same in app code.
Swap all of them to theme tokens (popover/accent/muted/destructive/
success) and replace the toast's literal "×" with the lucide X icon.

Wire browser chrome into the theme: color-scheme via CSS on
:root/.dark (follows the in-app toggle, not just the OS), a
theme-color meta kept in sync by the preload script and applyTheme(),
plus a unit test for the meta sync.

Extend check-no-raw-colors to also flag shadeless white/black
utilities outside components/ui/ so the objects-table case can't
recur.

Closes #68

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/src/objects/objects-table.tsx

@@ -287,7 +287,7 @@ export function ObjectsTable() {
             value={limit}
             onChange={(event) => setLimit(Number(event.target.value))}
             aria-label={t("objects.pageSize")}
-            className="rounded-md border bg-white px-1 py-0.5"
+            className="rounded-md border bg-background px-1 py-0.5"
           >
             {PAGE_SIZES.map((size) => (
               <option key={size} value={size}>