refactor(input): R10 S3b — one input recipe, ring focus everywhere

Unify text inputs onto the form.tsx inputCls look (surface bg, rounded-lg, 2px accent
RING focus), replacing the settings-family border-focus style app-wide:
- deleted 3 duplicate local `const inputCls` (KeyGate/SettingsPanel/SetupWizard) → import
  the shared one; a 4th (Welcome, py-2.5) kept local but re-styled to match.
- ~30 inline settings inputs: default full-size fields → inputCls; size variants (pager/
  table-filter/chat textarea/plex/glass-card) keep their width/radius/padding but swap
  bg-card→bg-surface and border-focus→ring-focus. glass-card/bg-transparent bgs left as-is.
- refreshed the form.tsx doc-comment (the old two-style split is gone).

The ring is the more visible / a11y-correct focus cue, matching R9's focus foundation.

frontend/src/components/Scheduler.tsx

@@ -172,7 +172,7 @@ function JobRow({
                   if (e.key === "Enter") save();
                   if (e.key === "Escape") setEditing(false);
                 }}
-                className="w-16 bg-card border border-border rounded-sm px-1.5 py-0.5 text-xs outline-hidden focus:border-accent"
+                className="w-16 bg-surface border border-border rounded-sm px-1.5 py-0.5 text-xs focus:outline-hidden focus:ring-2 focus:ring-accent/40"
               />
               <span className="text-muted text-xs">{t("scheduler.minutes")}</span>
               <button
@@ -281,7 +281,7 @@ function MaintenanceSettings({
           onChange={(e) => setVal(e.target.value)}
           onKeyDown={(e) => e.key === "Enter" && save()}
           aria-label={t("scheduler.maintenance.batchLabel")}
-          className="w-28 bg-card border border-border rounded-sm px-2 py-1 text-sm tabular-nums outline-hidden focus:border-accent"
+          className="w-28 bg-surface border border-border rounded-sm px-2 py-1 text-sm tabular-nums focus:outline-hidden focus:ring-2 focus:ring-accent/40"
         />
         <button
           onClick={save}