fix(files): address autosave migration and review regressions

Seed omitted autoSaveEnabled from the hydrated client preference (including
legacy localStorage) instead of resetting everyone to enabled. Restore SVG
non-editable flags, treat clean draft saves as success, and throw again from
disposed content-cache owners while keeping runtime-switch cache invalidation.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/lib/persistence.ts

@@ -1728,6 +1728,12 @@ export const syncDesktopSettings = async (): Promise<void> => {
     if (!isSettingsRuntimeContextCurrent(context)) return;
     const shouldPersistCraftGoalMigration = settings.draftStartersCraftGoalAdded !== true
       || settings.draftStartersScheduleTaskAdded !== true;
+    // `autoSaveEnabled` is new to the settings backend. Until the server has a
+    // value, materialize would invent the client default (true) and overwrite a
+    // deliberate legacy "off" preference migrated from
+    // `openchamber:files:auto-save-enabled`. Prefer the hydrated store value and
+    // seed the backend once so later omitted→default authority is correct.
+    const shouldSeedAutoSaveEnabled = typeof settings.autoSaveEnabled !== 'boolean';
     const authoritativeSettings = materializeAuthoritativeUiSettings(settings);
     try {
       persistToLocalStorage(settings);
@@ -1736,6 +1742,9 @@ export const syncDesktopSettings = async (): Promise<void> => {
     }
     await waitForHydration();
     if (!isSettingsRuntimeContextCurrent(context)) return;
+    if (shouldSeedAutoSaveEnabled) {
+      authoritativeSettings.autoSaveEnabled = useUIStore.getState().autoSaveEnabled;
+    }
     if (settings.draftStarters === undefined) {
       useUIStore.setState({ globalDraftStarters: null });
     }
@@ -1744,12 +1753,19 @@ export const syncDesktopSettings = async (): Promise<void> => {
     } catch (error) {
       console.warn('applyDesktopUiPreferences failed:', error);
     }
+    const migrationPatch: Partial<DesktopSettings> = {};
     if (shouldPersistCraftGoalMigration) {
-      await updateDesktopSettings({
-        ...(authoritativeSettings.draftStarters ? { draftStarters: authoritativeSettings.draftStarters } : {}),
-        draftStartersCraftGoalAdded: true,
-        draftStartersScheduleTaskAdded: true,
-      });
+      if (authoritativeSettings.draftStarters) {
+        migrationPatch.draftStarters = authoritativeSettings.draftStarters;
+      }
+      migrationPatch.draftStartersCraftGoalAdded = true;
+      migrationPatch.draftStartersScheduleTaskAdded = true;
+    }
+    if (shouldSeedAutoSaveEnabled) {
+      migrationPatch.autoSaveEnabled = authoritativeSettings.autoSaveEnabled;
+    }
+    if (Object.keys(migrationPatch).length > 0) {
+      await updateDesktopSettings(migrationPatch);
       if (!isSettingsRuntimeContextCurrent(context)) return;
     }