feat(studio): preserve external file conflicts (#2990)

* fix(studio): drain pending edits before reload

* fix(studio): address drain review feedback (#2989)

- prioritize conflicts and clear recovered DOM queue errors
- cover delayed blur effects and missing drain branches
- document stacked consumers and extend write-token retention

* test(studio): satisfy drain audit gate (#2989)

- share the editor-save hook harness across drain regressions
- extract settled failure inspection from the drain loop

* feat(studio): preserve external file conflicts

* fix(studio): isolate retry write receipts

* test(studio): cover external conflict recovery safety

packages/studio/src/contexts/FileManagerContext.tsx

@@ -27,9 +27,13 @@ export function FileManagerProvider({
     editingPathRef,
     projectIdRef,
     saveRafRef,
+    flushPendingSourceSave,
+    discardPendingSourceSave,
+    getPendingSourceCandidate,
     importedFontAssetsRef,
     readProjectFile,
     writeProjectFile,
+    overwriteExternalConflict,
     readOptionalProjectFile,
     observeProjectFileVersion,
     updateEditingFileContent,
@@ -67,9 +71,13 @@ export function FileManagerProvider({
       editingPathRef,
       projectIdRef,
       saveRafRef,
+      flushPendingSourceSave,
+      discardPendingSourceSave,
+      getPendingSourceCandidate,
       importedFontAssetsRef,
       readProjectFile,
       writeProjectFile,
+      overwriteExternalConflict,
       readOptionalProjectFile,
       observeProjectFileVersion,
       updateEditingFileContent,
@@ -101,9 +109,13 @@ export function FileManagerProvider({
       editingPathRef,
       projectIdRef,
       saveRafRef,
+      flushPendingSourceSave,
+      discardPendingSourceSave,
+      getPendingSourceCandidate,
       importedFontAssetsRef,
       readProjectFile,
       writeProjectFile,
+      overwriteExternalConflict,
       readOptionalProjectFile,
       observeProjectFileVersion,
       updateEditingFileContent,