feat(ui): streamline workspace settings and remove sharing

Unify compact workspace controls and panel transitions, move directory actions into the context menu, and remove backlink UI.

Reorganize settings with searchable sections, per-setting resets, shortcut search, and accurate save feedback.

Remove sharing UI, APIs, authentication helpers, and storage code; provide a transactional cleanup script with retirement tests. Reject directories during orphan image cleanup and cover mixed-batch preservation.

internal/vault/import_test.go

@@ -70,7 +70,7 @@ func TestImportZipAssetsAndMove(t *testing.T) {
 	if err := v.Mkdir("移动目标"); err != nil {
 		t.Fatal(err)
 	}
-	if _, err := v.Move("知识库/目录/笔记.md", "移动目标/改名.md", nil); err != nil {
+	if _, err := v.Move("知识库/目录/笔记.md", "移动目标/改名.md"); err != nil {
 		t.Fatal(err)
 	}
 	moved, _, err := v.Read("移动目标/改名.md")