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

libs/shared/interfaces/src/lib/settings.interface.ts

@@ -38,6 +38,7 @@ export interface Settings {
     mpvPlayerPath: string;
     mpvReuseInstance: boolean;
     vlcPlayerPath: string;
+    vlcReuseInstance: boolean;
     remoteControl: boolean;
     remoteControlPort: number;
     /** Custom download folder path (uses system Downloads folder if not set) */