fix(jellyfin): keep invalid mpv.executablePath from falling back in preview

- Timing preview passes an invalid configured path through so the spawn
  fails, instead of the preview silently running mpv from PATH
- Docs: Accessibility is not strictly required on macOS; without it the
  window helper uses a Core Graphics lookup that cannot detect a
  minimized mpv window

docs-site/installation.md

@@ -187,7 +187,7 @@ First-run setup can install the `subminer` command for you.
    xattr -d com.apple.quarantine /Applications/SubMiner.app
    ```
 
-3. Open **System Settings > Privacy & Security > Accessibility** and enable SubMiner (add it if it is missing). On macOS 27 this list is named **Device Control and Data Access**. The overlay cannot follow the mpv window without this.
+3. Open **System Settings > Privacy & Security > Accessibility** and enable SubMiner (add it if it is missing). On macOS 27 this list is named **Device Control and Data Access**. SubMiner uses it to track the mpv window. Without it, SubMiner falls back to a basic window lookup that cannot tell when mpv is minimized.
 
 First-run setup can install the `subminer` command for you.
 

docs-site/troubleshooting.md

@@ -262,5 +262,5 @@ mpv --gpu-context=x11vk,x11egl,x11 video.mkv
 
 ## macOS
 
-- Accessibility permission is required for window tracking: System Settings > Privacy & Security > Accessibility. On macOS 27 this list is named **Device Control and Data Access**.
+- Grant Accessibility permission under System Settings > Privacy & Security > Accessibility (named **Device Control and Data Access** on macOS 27). Without it, SubMiner falls back to a basic window lookup that cannot tell when mpv is minimized.
 - If Gatekeeper blocks the app, right-click it and choose Open, or run `xattr -d com.apple.quarantine /path/to/SubMiner.app`.