feat: 新增 S3 兼容云存储同步 (#1351)

* Add S3 Cloud Sync design document

Design for adding AWS S3 as a new Cloud Sync backend alongside WebDAV.
Hybrid approach: extract shared sync protocol, add independent S3 transport.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Add S3 cloud sync implementation design (reqwest + Sig V4)

Updated design based on 2026-03-06 draft: switches from rust-s3 crate
to hand-rolled AWS Sig V4 on existing reqwest for broader S3-compatible
service support (AWS, MinIO, R2, Alibaba OSS, Tencent COS, Huawei OBS).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Add S3 cloud sync implementation plan (11 tasks, TDD)

Detailed step-by-step plan covering: sync_protocol extraction, S3 Sig V4
transport, settings, sync/auto-sync modules, Tauri commands, frontend
presets/dynamic form, and i18n.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* deps: add hmac crate for S3 Sig V4 signing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor: extract sync_protocol.rs from webdav_sync.rs for shared use

Move transport-agnostic sync protocol logic (constants, types, snapshot
building, manifest validation, artifact verification, snapshot application,
utilities) into a new shared sync_protocol module so both WebDAV and the
upcoming S3 transport can reuse it.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: use transport-neutral error keys in sync_protocol

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 transport layer with AWS Sig V4 signing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3SyncSettings to AppSettings

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 sync module with upload/download/fetch

Implements the S3 sync protocol layer (s3_sync.rs) that combines the
shared sync_protocol with the S3 transport. Mirrors the WebDAV sync
module structure with independent sync mutex, connection check,
upload, download, fetch_remote_info, and sync status persistence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 auto sync worker with debounce

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 sync Tauri commands and auto sync worker startup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 sync TypeScript types and API layer

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 sync i18n translations (en/zh/ja)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add S3 sync presets and dynamic form to sync settings

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: preserve HTTP scheme for S3 custom endpoints (MinIO support)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* test: add live S3 integration tests (env-var driven, --ignored)

Run with: S3_TEST_AK=... S3_TEST_SK=... S3_TEST_BUCKET=... cargo test --lib services::s3::integration_tests -- --ignored

Verifies test_connection, put_object, get_object, head_object, and 404
handling against a real S3 bucket using the project's own Sig V4 signing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore: remove internal design docs before PR

* fix: wire S3 auto-sync to DB hook & sync UI state on async load

- P1: Add s3_auto_sync::notify_db_changed call in SQLite update_hook
  so S3 auto-sync worker receives DB change signals (was only wired
  for WebDAV, leaving S3 worker idle)

- P2: Add useEffect to update syncType selector when s3Config loads
  asynchronously, preventing stale "webdav" default for S3 users

* fix: satisfy clippy for s3 sync

* fix: address s3 sync review feedback

---------

Co-authored-by: Keith (via OpenClaw) <keithyt06@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Jason <farion1231@gmail.com>

src/lib/api/settings.ts

@@ -1,5 +1,10 @@
 import { invoke } from "@tauri-apps/api/core";
-import type { Settings, WebDavSyncSettings, RemoteSnapshotInfo } from "@/types";
+import type {
+  Settings,
+  WebDavSyncSettings,
+  S3SyncSettings,
+  RemoteSnapshotInfo,
+} from "@/types";
 import type { AppId } from "./types";
 
 export interface ConfigTransferResult {
@@ -142,6 +147,40 @@ export const settingsApi = {
     return await invoke("webdav_sync_fetch_remote_info");
   },
 
+  // ===== S3 Sync API =====
+
+  async s3TestConnection(
+    settings: S3SyncSettings,
+    preserveEmptyPassword = true,
+  ): Promise<WebDavTestResult> {
+    return await invoke("s3_test_connection", {
+      settings,
+      preserveEmptyPassword,
+    });
+  },
+
+  async s3SyncUpload(): Promise<WebDavSyncResult> {
+    return await invoke("s3_sync_upload");
+  },
+
+  async s3SyncDownload(): Promise<WebDavSyncResult> {
+    return await invoke("s3_sync_download");
+  },
+
+  async s3SyncSaveSettings(
+    settings: S3SyncSettings,
+    passwordTouched: boolean,
+  ): Promise<{ success: boolean }> {
+    return await invoke("s3_sync_save_settings", {
+      settings,
+      passwordTouched,
+    });
+  },
+
+  async s3SyncFetchRemoteInfo(): Promise<RemoteSnapshotInfo | { empty: true }> {
+    return await invoke("s3_sync_fetch_remote_info");
+  },
+
   async syncCurrentProvidersLive(): Promise<void> {
     const result = (await invoke("sync_current_providers_live")) as {
       success?: boolean;