refactor: remove approve/reject, add per-asset Postiz push button

- Remove approve/reject buttons and status badge from asset cards
- Remove bulk approve/reject from gallery toolbar
- Remove status filter dropdown (no longer relevant)
- Add "Postiz" button on each image/video asset card for direct publishing
- Keep bulk "Push to Postiz" for multi-select in toolbar
- Update How This Works guide to remove approve/reject section

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/(dashboard)/assets/page.tsx

@@ -35,7 +35,7 @@ export default function GlobalAssetsPage() {
       )}
 
       <Dialog open={helpOpen} onOpenChange={setHelpOpen}>
-        <DialogContent className="max-w-lg">
+        <DialogContent className="sm:max-w-lg max-h-[85vh] overflow-y-auto">
           <DialogHeader>
             <DialogTitle>Asset Library Guide</DialogTitle>
             <DialogDescription>
@@ -43,14 +43,6 @@ export default function GlobalAssetsPage() {
             </DialogDescription>
           </DialogHeader>
           <div className="space-y-4 text-sm">
-            <section>
-              <h3 className="font-semibold mb-1">Review &amp; Approve</h3>
-              <p className="text-muted-foreground">
-                Every asset starts as a draft. Use <strong>Approve</strong> or <strong>Reject</strong> to
-                triage. Select multiple assets with checkboxes for bulk actions.
-              </p>
-            </section>
-
             <section>
               <h3 className="font-semibold mb-1">Repurpose</h3>
               <p className="text-muted-foreground">