Polish content pages: share AuthTopBar, page-grid helper and responsive tables

- Extract shared AuthTopBar frosted top bar; reuse in login & register
- Add .page-grid class replacing 48 inline grid styles
- Add .table-scroll + .table-cell-truncate helpers; wrap leaderboard/staff tables
- Constrain settings page width (max-w-5xl) and stack profile card on mobile
- Use theme background var for shop category icon (dark-mode safe)

src/app/(site)/apply/staff/page.tsx

@@ -96,7 +96,7 @@ export default async function ApplyStaffPage({
 	const appliedRankIds = new Set(myApps.map((a) => a.rankId));
 
 	return (
-		<main style={{ display: "grid", gap: "1.5rem" }}>
+		<main className="page-grid">
 			{submitted === "1" ? (
 				<div role="status" style={feedbackStyle("success")}>
 					{t("success.submitted")}

src/app/(site)/apply/team/page.tsx

@@ -75,7 +75,7 @@ export default async function ApplyTeamPage({
 	const appliedTeamIds = new Set(myApps.map((a) => a.rankId));
 
 	return (
-		<main style={{ display: "grid", gap: "1.5rem" }}>
+		<main className="page-grid">
 			{submitted === "1" ? (
 				<div role="status" style={feedbackStyle("success")}>
 					{t("success.submitted")}