feat(plugins): 4 个业务插件代码 + 前台公开页面改造

plugins/navManager：导航 CRUD + 导航分类 CRUD（独立 blueprint）
plugins/friendManager：友情链接 CRUD
plugins/aboutManager：关于本站 CRUD
plugins/siteStats：访问统计主页 + JSON 接口 + /site/* GET 埋点 + nav 卡片点击埋点

applications/view/public/nav.py：导航聚合页 / 分类详情 / JSON 接口，支持 visit_count 注入
applications/view/public/about.py：关于本站公开页
applications/view/public/friend.py：友情链接公开页

templates/public/base.html：响应式首页（搜索框 / 分类抽屉 / 5 主题切换 / footer 隐私小字）
templates/public/index.html / category.html：卡片右下角访问次数
templates/public/about.html / friend.html：关于 + 友链前台页

docs/plugins-development.md：插件开发完整指南（生命周期 + 4 个示例 + FAQ + framework 迁移）

scripts/：探针与端到端验证脚本（probe_*/verify_*/test_*）

scripts/probe_nav_category.py

@@ -0,0 +1,142 @@
+"""
+导航分类功能端到端探针
+======================
+
+不依赖浏览器 + ddddocr + 调试 header，直接用 Flask test_client 走完整流程：
+
+  1. 登录 admin
+  2. GET  /system/nav-category/         (主页面 HTML)
+  3. GET  /system/nav-category/data    (table_api JSON)
+  4. POST /system/nav-category/save    (新增)
+  5. PUT  /system/nav-category/update  (更新)
+  6. PUT  /system/nav-category/enable  (启用/禁用)
+  7. DELETE /system/nav-category/remove/<id>  (删除)
+  8. 验证每个 API 的 {code, message, data} 协议
+
+退出码：全部通过 → 0；任一失败 → 1
+"""
+import json
+import sys
+import traceback
+
+sys.path.insert(0, r'D:\bwstudio\pear-admin-flask')
+
+from applications import create_app
+
+app = create_app()
+client = app.test_client()
+
+
+def _login():
+    """admin/123456 登录拿 cookie session。"""
+    # 拿一张 captcha —— 通过 test_client 共享 session_transaction
+    r = client.get('/system/passport/getCaptcha')
+    assert r.status_code == 200, r.status_code
+
+    with client.session_transaction() as sess:
+        code = sess.get('code') or ''
+    code = code.lower()
+    assert code, 'captcha code missing'
+
+    r = client.post('/system/passport/login', data={
+        'username': 'admin',
+        'password': '123456',
+        'captcha': code,
+    }, follow_redirects=False)
+    assert r.status_code in (200, 302), r.status_code
+
+
+def _show(label, resp):
+    body = resp.get_data(as_text=True)
+    print(f'  [{resp.status_code}] {label}  -> {body[:200]}{"..." if len(body) > 200 else ""}')
+
+
+def main():
+    _login()
+    print('=== 已登录，开始 E2E 探针 ===\n')
+
+    # 1. 分类主页面 HTML
+    r = client.get('/system/nav-category/')
+    print(f'[HTML main] {r.status_code}  content-type={r.content_type}')
+    assert r.status_code == 200
+    assert b'nav-category/data' in r.data or b'\u5bfc\u822a\u5206\u7c7b' in r.data, 'main 页面未包含预期内容'
+    print('  [OK] 分类主页面返回 200，含预期关键字\n')
+
+    # 2. data 接口（table_api 协议：{code, data, count, msg, limit}）
+    r = client.get('/system/nav-category/data')
+    assert r.status_code == 200
+    payload = r.get_json()
+    assert payload['code'] == 0, payload
+    before_ids = {row['id'] for row in payload['data']}
+    print(f'  [OK] data 接口 code=0，count={payload["count"]}，已有分类 {len(before_ids)} 条：{sorted(before_ids)}\n')
+
+    # 3. 新增（success_api 协议：{success, msg}）
+    unique_name = f'E2E临时分类{int(__import__("time").time())}'
+    r = client.post('/system/nav-category/save',
+                    json={'name': unique_name, 'icon': 'layui-icon-test',
+                          'description': 'e2e created', 'sort': 1, 'enable': 1})
+    payload = r.get_json()
+    assert payload.get('success') is True, payload
+    print(f'  [OK] 新增成功：{unique_name}\n')
+
+    # 4. 拿到 id
+    r = client.get('/system/nav-category/data')
+    payload = r.get_json()
+    new_id = next((row['id'] for row in payload['data'] if row['name'] == unique_name), None)
+    assert new_id is not None, '新增的分类查不到'
+    print(f'  [OK] 查回新增分类 id={new_id}\n')
+
+    # 5. 更新
+    r = client.put('/system/nav-category/update',
+                   json={'catId': new_id, 'name': unique_name + '_改',
+                         'icon': 'layui-icon-edit', 'description': 'e2e updated',
+                         'sort': 99, 'enable': 1})
+    payload = r.get_json()
+    assert payload.get('success') is True, payload
+    print(f'  [OK] 更新成功\n')
+
+    # 6. 禁用 → 启用
+    r = client.put('/system/nav-category/disable', json={'catId': new_id})
+    assert r.get_json().get('success') is True
+    r = client.put('/system/nav-category/enable', json={'catId': new_id})
+    assert r.get_json().get('success') is True
+    print(f'  [OK] 禁用→启用通过\n')
+
+    # 7. 删除
+    r = client.delete(f'/system/nav-category/remove/{new_id}')
+    assert r.get_json().get('success') is True, r.get_json()
+    print(f'  [OK] 删除成功\n')
+
+    # 8. 查回 count 必须等于开始前
+    r = client.get('/system/nav-category/data')
+    payload = r.get_json()
+    after_ids = {row['id'] for row in payload['data']}
+    assert before_ids == after_ids, f'分类集合变化：before={before_ids}, after={after_ids}'
+    print(f'  [OK] 删除后 count 还原，新增的 id 已不在集合中\n')
+
+    # 9. 重名检测
+    existing_name = None
+    if payload['data']:
+        existing_name = payload['data'][0]['name']
+    if existing_name:
+        r = client.post('/system/nav-category/save',
+                        json={'name': existing_name, 'icon': 'x', 'description': '', 'sort': 0, 'enable': 1})
+        body = r.get_json()
+        assert body.get('success') is False, body
+        print(f'  [OK] 重名拦截正常：{body["msg"]}\n')
+
+    print('=== ALL PASS ===')
+
+
+if __name__ == '__main__':
+    try:
+        main()
+        sys.exit(0)
+    except AssertionError as e:
+        print(f'\n!!! ASSERT FAIL: {e}')
+        traceback.print_exc()
+        sys.exit(1)
+    except Exception as e:
+        print(f'\n!!! UNEXPECTED: {e}')
+        traceback.print_exc()
+        sys.exit(1)