Polish pass 5 — sentence case, theme tokens, remaining a11y

- Sentence case on all button labels (Mark read, Go to settings, Try again,
  Mark all read, Disconnect, Connect wallet, Logging in, Posting, Quote & post,
  Loading, Refresh); V4V tabs capitalized
- V4VDashboard: amber-500 hard-coded colors → zap theme token
- BookmarkView: tab container rounded-sm overflow-hidden
- ToastContainer, DebugPanel, PodcastPlayerBar: aria-labels on dismiss/close buttons
- PodcastPlayerBar: ASCII x → × Unicode, ... → … Unicode
- AboutView: document bg-white on QR code as intentional

src/components/v4v/V4VDashboard.tsx

@@ -63,9 +63,9 @@ export function V4VDashboard() {
             Playing <span className="text-text">{episode.title}</span> — no V4V recipients.
           </div>
         ) : v4vStreaming ? (
-          <div className="bg-amber-500/5 border border-amber-500/20 rounded-sm p-3">
+          <div className="bg-zap/5 border border-zap/20 rounded-sm p-3">
             <div className="flex items-center gap-2 mb-2">
-              <span className="text-amber-400 animate-pulse text-[12px]">&#9889;</span>
+              <span className="text-zap animate-pulse text-[12px]">&#9889;</span>
               <span className="text-[12px] text-text font-medium">Streaming</span>
               {autoEnabled && (
                 <span className="text-[9px] text-accent bg-accent/10 px-1.5 py-0.5 rounded-sm">AUTO</span>

src/components/v4v/V4VView.tsx

@@ -26,7 +26,7 @@ export function V4VView() {
                     : "border-transparent text-text-dim hover:text-text"
                 }`}
               >
-                {t}
+                {t.charAt(0).toUpperCase() + t.slice(1)}
               </button>
             ))}
           </div>