feat(player): add VLC reuse-instance setting (#893)

VLC was unconditionally spawned per click — VLC's own single-instance
preference fails because the per-launch RC args defeat its D-Bus
forwarder. Mirror the existing MPV reuse pattern so users can opt in to
driving one tracked VLC via its RC interface (clear + add) instead of
opening a new window every stream.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: f957cd9849e0

apps/web/src/app/settings/settings-playback-section.component.html

@@ -146,5 +146,17 @@
                 </mat-form-field>
             </div>
         </div>
+
+        <div class="setting-item">
+            <div class="setting-item__meta">
+                <h4>{{ 'SETTINGS.VLC_REUSE_INSTANCE_LABEL' | translate }}</h4>
+                <p>
+                    {{ 'SETTINGS.VLC_REUSE_INSTANCE_DESCRIPTION' | translate }}
+                </p>
+            </div>
+            <div class="setting-item__control setting-item__toggle">
+                <mat-checkbox formControlName="vlcReuseInstance"></mat-checkbox>
+            </div>
+        </div>
     }
 </section>