feat: NAS 部署 + auth-hub 认证 + 同步逻辑修复

部署:
- 后端 Python/Flask，数据层可插拔 SQLite/MariaDB
- NAS 部署路径 /volume1/web/garmin-health-lab，端口 8124
- Gunicorn 生产服务器 (2 workers / 4 threads)
- 开机自启脚本 deploy/S99garmin.sh
- frp 隧道甲骨文 8124 → NAS 8124，外网访问
- 前端构建产物纳入版本管理 (backend/static/)

认证:
- auth-hub OAuth2/OIDC 统一登录接入
- 新建 NAS 专用 client，注册内外网回调地址
- 前端 LoginPage 支持回调路由 /auth/callback
- 数据同步页增加 Garmin 邮箱输入框

同步逻辑修复:
- 自动同步调度器读取用户 history_days 设置，不再固定 2 天
- 前端 0（全部历史）不再被 || 吞掉，改为 ?? 处理
- 后端路由和 sync_data 中 0 不再被当成 falsy 回退默认值
- sync_data 和调度器中 0 → 730 天（全部历史=最大范围）
- 已同步天数显示数据库实际总天数 (totalDays)
- 历史范围新增「自上次同步」增量选项 (days=-1)
- 后端 settings.py HISTORY 添加 -1 值

项目文档:
- 创建 PROGRESS.md 跟踪项目进度

backend/services/garmin.py

@@ -54,17 +54,24 @@ def _set_sync_status(user_id, status, now, **fields):
 
 def get_sync_status(user_id):
     row = query_one("SELECT * FROM sync_status WHERE user_id = ?", [user_id])
+    # Count distinct days actually stored in the database for this user.
+    count = query_one(
+        "SELECT COUNT(DISTINCT date) AS cnt FROM health_data WHERE user_id = ?", [user_id]
+    )
+    total_days = count["cnt"] if count else 0
     if not row:
         return {
             "status": "idle",
             "lastSyncTime": None,
             "recordsSynced": 0,
+            "totalDays": total_days,
             "lastError": None,
         }
     return {
         "status": row["status"],
         "lastSyncTime": row["last_sync_time"],
         "recordsSynced": row["records_synced"],
+        "totalDays": total_days,
         "lastError": row["last_error"],
         "progressCurrent": row.get("progress_current"),
         "progressTotal": row.get("progress_total"),
@@ -360,6 +367,10 @@ def _connect(creds, user_id=None):
     Garmin = _import_garmin()
     client = Garmin(is_cn=_is_cn())
 
+    # Garmin SSO can be slow from some networks; the default 10s timeout in
+    # the underlying garth library is too tight for the initial login.
+    client.garth.configure(timeout=30)
+
     token = load_token(user_id) if user_id else None
     if token:
         client.garth.loads(token)
@@ -937,7 +948,7 @@ def start_sync(user_id, creds, days=None):
     Progress lands in sync_status, which the UI polls; a full backfill runs
     far longer than any sensible HTTP timeout.
     """
-    days = days or DEFAULT_SYNC_DAYS
+    days = DEFAULT_SYNC_DAYS if days is None else days
     now = datetime.datetime.utcnow().isoformat(timespec="seconds")
     until, msg = _rate_limit_block(user_id)
     if until:
@@ -968,7 +979,9 @@ def sync_data(user_id, creds, days=None, client=None):
 
     `client` exists so tests can inject a stub instead of reaching Garmin.
     """
-    days = days or DEFAULT_SYNC_DAYS
+    days = DEFAULT_SYNC_DAYS if days is None else days
+    if days == 0:
+        days = 730  # 全部历史 → 最大范围
     now = datetime.datetime.utcnow().isoformat(timespec="seconds")
     until, msg = _rate_limit_block(user_id)
     if until:
@@ -1004,6 +1017,23 @@ def sync_data(user_id, creds, days=None, client=None):
         }
 
     today = datetime.date.today()
+
+    # -1 means "incremental sync": pick up from the latest date already in the
+    # local database rather than pulling a fixed window.
+    if days == -1:
+        row = query_one("SELECT MAX(date) FROM health_daily WHERE user_id = ?", (user_id,))
+        latest = row[0] if row and row[0] else None
+        if latest is None:
+            days = DEFAULT_SYNC_DAYS  # first sync → fall back to default window
+        else:
+            days = max(1, (today - datetime.date.fromisoformat(latest)).days)
+        # Rewrite the progress total now that we know the real day count.
+        _set_sync_status(
+            user_id, "syncing", now,
+            records_synced=0, progress_current=0, progress_total=days,
+            stage="连接 Garmin",
+        )
+
     start_date = (today - datetime.timedelta(days=days - 1)).isoformat()
 
     days_synced = 0