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。

src/main/assistant-storage-worker.ts

@@ -1,25 +1,26 @@
 import { parentPort, workerData } from 'node:worker_threads'
-import { upgradeAssistantStorage } from './assistant/assistant-storage-upgrade'
+import { upgradeAssistantStorage, type AssistantStorageUpgrade } from './assistant/assistant-storage-upgrade'
 
 const input = workerData as {
   databasePath: string
   cancellation: SharedArrayBuffer
+  upgrade: AssistantStorageUpgrade
 }
 const cancellation = new Int32Array(input.cancellation)
 try {
-  // Startup checks for legacy data before spawning this worker, including retries.
+  // Preserve this startup's actual conversion/reclamation decision across retries.
   upgradeAssistantStorage(
     input.databasePath,
     (progress) => parentPort?.postMessage({ progress }),
     () => Atomics.load(cancellation, 0) !== 0,
-    { pendingUpgradeConfirmed: true }
+    { confirmedUpgrade: input.upgrade }
   )
   parentPort?.postMessage({ done: true })
 } catch (error) {
   parentPort?.postMessage({
     error: error instanceof Error && /full|space/iu.test(error.message)
       ? '磁盘空间不足，无法完成空间回收。请释放一些空间后重试。'
-      : '历史执行记录优化未完成。请重试；若仍失败，请备份数据并联系支持。',
+      : '本地数据升级未完成。请重试；若仍失败，请备份数据并联系支持。',
     cancelled: error instanceof Error && error.name === 'AbortError'
   })
 }