feat(youtube): add YouTube embed support with yt-dlp integration for ad-free streaming

src/app/features/settings/general/General.tsx

@@ -1060,10 +1060,18 @@ function Messages() {
         />
       </SequenceCard>
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
-        <SettingTile
-          title="Url Preview"
-          after={<Switch variant="Primary" value={urlPreview} onChange={setUrlPreview} />}
-        />
+          <SettingTile
+            title="Url Preview"
+            after={<Switch variant="Primary" value={urlPreview} onChange={setUrlPreview} />}
+          />
+          <Box style={{ marginLeft: '2.5rem', marginTop: '0.5rem', marginBottom: '1rem', background: 'rgba(255,255,255,0.045)', borderRadius: '8px', padding: '1.1rem 1.3rem', maxWidth: '36rem', boxShadow: '0 1px 4px 0 rgba(0,0,0,0.07)' }}>
+            <Text size="T200" style={{ color: '#d0d0d0', display: 'block', marginBottom: '0.5rem', lineHeight: 1.6, fontWeight: 400 }}>
+              For ad-free YouTube streaming, install <b>yt-dlp</b> (required for direct playback):
+            </Text>
+            <Box as="pre" style={{ background: '#232323', color: '#fff', borderRadius: '5px', padding: '0.6rem 1rem', fontSize: '1.08em', margin: 0, fontFamily: 'JetBrains Mono, Fira Mono, Menlo, monospace', overflowX: 'auto', width: '100%', textAlign: 'center', letterSpacing: '0.01em' }}>
+              winget install yt-dlp
+            </Box>
+          </Box>
       </SequenceCard>
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile