Add versioned DB migrations, startup error dialog and native basics

rusqlite_migration with a VACUUM INTO backup before upgrading; M2 adds GST
registration, snapshot, cancellation and draft columns and backfills
snapshots for existing invoices. Startup failures now show a native dialog
instead of exiting silently. Adds single-instance and window-state plugins,
minimum window 960x600, embedBootstrapper, DMABUF workaround on Linux and
xbps dependency updates.

src-tauri/tauri.conf.json

@@ -15,8 +15,8 @@
         "title": "Voiced",
         "width": 1360,
         "height": 900,
-        "minWidth": 1024,
-        "minHeight": 720,
+        "minWidth": 960,
+        "minHeight": 600,
         "resizable": true,
         "center": true
       }
@@ -41,7 +41,7 @@
     ],
     "windows": {
       "webviewInstallMode": {
-        "type": "downloadBootstrapper"
+        "type": "embedBootstrapper"
       },
       "nsis": {
         "installMode": "currentUser"