feat(export): 支持 CSV 计划导出和稳定导出索引 (#114)

两个核心增强:

1. **CSV 计划导出工作流** (`--write-plan-csv` / `--from-plan-csv`)
   - 支持 blacklist (export=0 跳过) / whitelist (export=1 导出) 两种模式
   - `--size-mode estimate|scan` 控制是否扫本地附件
   - UTF-8 BOM 编码, Excel/WPS 直接打开
   - 解决了之前"动不动全量导出"的痛点

2. **`_export_index.json` 稳定导出索引**
   - 用 username 追踪当前 JSON 文件
   - 联系人备注/群名变化时自动重命名旧文件 (而不是产生孤儿)
   - 同名联系人冲突时自动追加 `__<username>` 后缀
   - atomic write (tmp + os.replace), bootstrap from existing files

3. **JSON metadata 扩展**
   - 新增 `date_first_msg / date_last_msg / contact_remark / contact_nick_name / contact_tags / contact_memo`

测试: 717 行, 20 tests pass, 覆盖 CRUD 索引、黑白名单、命名冲突、incremental rename、UTF-8 BOM。

mcp_server.py

@@ -222,7 +222,7 @@ atexit.register(_cache.cleanup)
 # ============ 联系人缓存 ============
 
 _contact_names = None  # {username: display_name}
-_contact_full = None   # [{username, nick_name, remark}]
+_contact_full = None   # [{username, nick_name, remark, alias, description, phone}]
 _contact_tags = None   # {label_id: {name, sort_order, members: [{username, display_name}]}}
 _self_username = None
 _contact_db_mtime = 0  # mtime of the decrypted contact.db when caches were last populated
@@ -240,19 +240,55 @@ _QUERY_LIMIT_MAX = 500
 _HISTORY_QUERY_BATCH_SIZE = 500
 
 
-def _load_contacts_from(db_path):
-    names = {}
-    full = []
-    conn = sqlite3.connect(db_path)
-    try:
-        for r in conn.execute("SELECT username, nick_name, remark FROM contact").fetchall():
-            uname, nick, remark = r
-            display = remark if remark else nick if nick else uname
-            names[uname] = display
-            full.append({'username': uname, 'nick_name': nick or '', 'remark': remark or ''})
-    finally:
-        conn.close()
-    return names, full
+def _load_contacts_from(db_path):
+    names = {}
+    full = []
+    conn = sqlite3.connect(db_path)
+    try:
+        columns = {
+            row[1] for row in conn.execute("PRAGMA table_info(contact)").fetchall()
+        }
+        optional_columns = {
+            "alias": "",
+            "description": "",
+            "phone": "",
+            "phone_number": "",
+            "mobile": "",
+            "mobile_phone": "",
+            "telephone": "",
+        }
+        select_columns = ["username", "nick_name", "remark"]
+        select_columns.extend(
+            col for col in optional_columns
+            if col in columns and col not in select_columns
+        )
+        rows = conn.execute(
+            "SELECT " + ", ".join(f"[{col}]" for col in select_columns)
+            + " FROM contact"
+        ).fetchall()
+        for r in rows:
+            data = dict(zip(select_columns, r))
+            uname = data.get("username")
+            nick = data.get("nick_name")
+            remark = data.get("remark")
+            display = remark if remark else nick if nick else uname
+            names[uname] = display
+            phone = ""
+            for col in ("phone", "phone_number", "mobile", "mobile_phone", "telephone"):
+                if data.get(col):
+                    phone = data.get(col) or ""
+                    break
+            full.append({
+                'username': uname,
+                'nick_name': nick or '',
+                'remark': remark or '',
+                'alias': data.get("alias") or '',
+                'description': data.get("description") or '',
+                'phone': phone,
+            })
+    finally:
+        conn.close()
+    return names, full
 
 
 def _get_contact_db_path():
@@ -301,9 +337,23 @@ def get_contact_names():
         return {}
 
 
-def get_contact_full():
-    get_contact_names()
-    return _contact_full or []
+def get_contact_full():
+    get_contact_names()
+    return _contact_full or []
+
+
+def get_contact_tag_names_by_username():
+    tags = _load_contact_tags()
+    by_username = {}
+    for tag in tags.values():
+        name = tag.get('name') or ''
+        if not name:
+            continue
+        for member in tag.get('members', []):
+            username = member.get('username')
+            if username:
+                by_username.setdefault(username, []).append(name)
+    return by_username
 
 
 def _extract_pb_field_30(data):