fix(import): report accurate post-parse progress stages in real time

The UI stayed on "parsing messages" during the whole post-parse phase:
the importer emitted an 'importing' stage the frontend had no text for,
and on CLI Web the synchronous DB writes / index / FTS build starved the
event loop so buffered SSE progress events only arrived after the import
finished.

- Replace 'importing' with 'saving' (message writes) and a new 'indexing'
  stage (indexes / FTS / session index) in ParseProgress, with UI texts
  for all four locales.
- Yield a macrotask between native parser batches and before heavy
  synchronous steps so SSE progress events flush while importing.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/cli/src/import/stream-import.ts

@@ -108,11 +108,14 @@ export async function streamImport(
             stage = 'parsing'
             pct = Math.min(Math.round(progress.percentage * 0.7), 70)
             break
-          case 'importing':
           case 'saving':
             stage = 'saving'
             pct = 80
             break
+          case 'indexing':
+            stage = 'indexing'
+            pct = 90
+            break
           case 'done':
             stage = 'done'
             pct = 100