fix: avoid history reclamation during structure-only upgrades

Ordinary database schema upgrades previously ran VACUUM on free pages and
showed misleading history-cleanup progress. Separate structure upgrades from
required legacy conversions, retaining reclamation intent only for retries
within the same startup. Preserve released data without new schema versions
or persistent migration markers; Agent and normal writes remain unchanged.

Add real SQLite and Worker regressions, bilingual operation-specific startup
copy, and migration documentation. Synchronize native Electron drag input
with actual resize state without weakening layout assertions.

Validation: 47 focused migration tests passed; typecheck, lint and diff checks
passed. Final full suite: 5137 passed, 74 skipped, 2 unrelated Electron failures.
Both failing Electron tests passed an isolated rerun; full CI remains unverified.

Release note: 修复普通数据库结构升级再次整理历史和回收空间的问题；仅在需要转换旧数据时执行相关处理，启动页准确显示当前升级操作。

FEATURES.md

@@ -194,7 +194,9 @@ records are listed separately and do not introduce another feature status.
   reopen the upgraded database. The schema-35 repair released in 0.13.2 also handles
   repeated tool blocks written after upgrading to 0.13.1, without deleting events.
   Terminal tasks release their write caches; duplicate remote replay does not
-  rebuild a released cache. See
+  rebuild a released cache. Structure-only upgrades do not reconvert history or
+  reclaim ordinary free pages; the startup page distinguishes structure updates,
+  legacy conversion, and actual space reclamation. See
   [storage and upgrade behavior](./docs/features/assistant-workbar/execution-history-storage.md).
 
 - [x] **Direct model Runtime**: Supports question answering, knowledge