Add keyboard mode toggle and QR scanner improvements

- Add keyboard mode toggle button (⇧K) in sidebar
- Triple-Escape to quickly exit keyboard mode
- Extract QrScannerModal to shared component
- Add QR scanner for NWC wallet connection in Settings
- Update Help page with keyboard toggle documentation
- Fix keyboard navigation getting stuck on inbox
- Improve feed loading after login (loads immediately)
- DM conversation page layout improvements

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/StuffStats/ZapButton.tsx

@@ -135,10 +135,10 @@ export default function ZapButton({ stuff }: { stuff: Event | string }) {
     <>
       <button
         className={cn(
-          'flex items-center gap-1 select-none px-3 h-full cursor-pointer enabled:hover:text-yellow-400 disabled:text-muted-foreground/40 disabled:cursor-default',
+          'flex items-center gap-1 select-none px-3 h-full cursor-pointer enabled:hover:text-yellow-400 disabled:text-muted-foreground/40 disabled:cursor-default group',
           hasZapped ? 'text-yellow-400' : 'text-muted-foreground'
         )}
-        title={t('Zap')}
+        title={t('Zap (z)')}
         disabled={disable || zapping}
         data-action="zap"
         onMouseDown={handleClickStart}
@@ -147,11 +147,14 @@ export default function ZapButton({ stuff }: { stuff: Event | string }) {
         onTouchStart={handleClickStart}
         onTouchEnd={handleClickEnd}
       >
-        {zapping ? (
-          <Loader className="animate-spin" />
-        ) : (
-          <Zap className={hasZapped ? 'fill-yellow-400' : ''} />
-        )}
+        <span className="relative">
+          {zapping ? (
+            <Loader className="animate-spin" />
+          ) : (
+            <Zap className={hasZapped ? 'fill-yellow-400' : ''} />
+          )}
+          <kbd className="absolute -top-1.5 -right-2 text-[9px] font-mono opacity-50 group-hover:opacity-100">z</kbd>
+        </span>
         {!!zapAmount && <div className="text-sm">{formatAmount(zapAmount)}</div>}
       </button>
       {event && (