fix(snap): add filesystem and desktop integration plugs

Fixes #6031

- Add home and removable-media plugs for local file sync access
- Add desktop and desktop-legacy plugs for taskbar pinning in Cinnamon
- Update install hook to prompt for home interface connection
- Add documentation warnings about snap limitations and data persistence

All plugs include inline comments explaining their purpose and linking to issue.

README.md

@@ -234,6 +234,18 @@ sudo snap install --channel=edge superproductivity
 sudo snap set core experimental.refresh-app-awareness=true
 ```
 
+**Important: Enable Local File Sync**
+To use local file sync, you need to manually connect the `home` interface:
+
+```bash
+sudo snap connect superproductivity:home
+```
+
+**⚠️ Snap Data Persistence Warning**
+When uninstalling the snap package, all user data (tasks, projects, settings) stored in `~/snap/superproductivity/common/` may be removed. Always export your data before uninstalling. Consider using Flatpak, AppImage, or .deb packages if you prefer data to persist in the standard `~/.config/` location.
+
+For more details, see [issue #6031](https://github.com/super-productivity/super-productivity/issues/6031).
+
 <a href="https://snapcraft.io/superproductivity">
   <img alt="Get it from the Snap Store" src="https://snapcraft.io/static/images/badges/en/snap-store-black.svg" />
 </a>

electron-builder.yaml

@@ -80,6 +80,13 @@ snap:
     - password-manager-service
     - system-observe
     - login-session-observe
+    # Fix for issue #6031: Add filesystem access for local file sync
+    # https://github.com/super-productivity/super-productivity/issues/6031
+    - home # Allows file picker to access user's home directory for sync
+    - removable-media # Allows sync to external drives/USB storage
+    # Fix for issue #6031: Add desktop integration for taskbar pinning in Cinnamon
+    - desktop # Provides D-Bus interfaces for window manager integration
+    - desktop-legacy # Fallback for older desktop environments
 
 flatpak:
   runtimeVersion: '23.08'

snap/hooks/install

@@ -12,4 +12,13 @@ if snapctl is-connected system-observe; then
 else
     echo "Please connect system-observe interface for better system integration:"
     echo "sudo snap connect superproductivity:system-observe"
+fi
+
+# Fix for issue #6031: Prompt for home interface connection for local file sync
+if snapctl is-connected home; then
+    echo "home interface already connected"
+else
+    echo "Please connect home interface to enable local file sync:"
+    echo "sudo snap connect superproductivity:home"
+    echo "Without this, you won't be able to sync to local files outside the snap container."
 fi