fix: 修复环路检测失败 + 多项UX增强

修复:
- 环路检测正则 \s+(Onu\S+)\s+ → \s+(Onu\S+) (splitlines移除换行后尾随\s无法匹配)
- 权限中间件 Header(...) → Header(None) 避免缺失Auth头返回422而非401
- 环路检测请求超时30s→120s (SSH连接30+台OLT实测需58秒)

重构 (ssh_service.py):
- 提取 _send_and_wait 为私有方法,消除3处重复内部函数
- 添加 __enter__/__exit__ 上下文管理器支持
- 加固 execute_command prompt检测 (按行匹配<DEVICE_NAME>)
- 移除未使用的settings import
- olt.py/devices.py 调用方改用 with 语法

新功能:
- 侧边栏退出登录上方显示当前用户名和角色
- 版本号从VERSION文件自动读取 (后端/health返回,前端动态显示)
- 基于广西南宁经纬度计算日落时间,自动切换深色/浅色主题
- /api/olt/loopback-detection 响应增加raw字段便于排查

基础设施:
- CLAUDE.md 加入 .gitignore
- 新增 .claude/rules/07-remote-operations.md (远程部署操作)
- 新增 .claude/rules/08-frp-notes.md (frp隧道注意事项)
- 新增 VERSION 文件 (版本号 0.10.0)
- 新增环路检测解析测试用例 (5个)

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

backend/tests/test_ssh_parser.py

@@ -1,4 +1,5 @@
 """SSH 输出解析测试"""
+import re
 import pytest
 from app.services.ssh_service import SSHService
 
@@ -91,3 +92,71 @@ class TestCleanOutput:
         cleaned = svc._clean_output(output)
         assert "1484-778f-aa60" in cleaned
         assert "---- More ----" not in cleaned
+
+
+class TestDetectLoopback:
+    """环路检测输出解析测试"""
+
+    def _parse(self, output: str):
+        """模拟 detect_loopback 中的解析逻辑"""
+        has_loop = "Loop is detected on following interfaces" in output
+        interfaces = []
+        if has_loop:
+            for line in output.splitlines():
+                m = re.match(r'\s+(Onu\S+)', line)
+                if m:
+                    interfaces.append(m.group(1))
+        return has_loop, interfaces
+
+    def test_no_loop(self):
+        output = """
+Loopback detection is enabled.
+Loopback detection interval is 30 second(s).
+No loopback is detected.
+"""
+        has_loop, interfaces = self._parse(output)
+        assert not has_loop
+        assert interfaces == []
+
+    def test_has_loop_single(self):
+        output = """
+Loopback detection is enabled.
+Loopback detection interval is 30 second(s).
+Loop is detected on following interfaces:
+        Onu1/0/1:1
+"""
+        has_loop, interfaces = self._parse(output)
+        assert has_loop
+        assert interfaces == ["Onu1/0/1:1"]
+
+    def test_has_loop_multiple(self):
+        output = """
+Loop is detected on following interfaces:
+        Onu1/0/1:1
+        Onu1/0/2:3
+        Onu2/0/5:10
+"""
+        has_loop, interfaces = self._parse(output)
+        assert has_loop
+        assert interfaces == ["Onu1/0/1:1", "Onu1/0/2:3", "Onu2/0/5:10"]
+
+    def test_has_loop_with_extra_whitespace(self):
+        """接口行有多余空白字符"""
+        output = """
+Loop is detected on following interfaces:
+            Onu1/0/1:1
+"""
+        has_loop, interfaces = self._parse(output)
+        assert has_loop
+        assert interfaces == ["Onu1/0/1:1"]
+
+    def test_no_false_positive_on_prompt(self):
+        """确保设备提示符不被误识别为接口"""
+        output = """
+Loop is detected on following interfaces:
+        Onu1/0/1:1
+<H3C_Device>
+"""
+        has_loop, interfaces = self._parse(output)
+        assert has_loop
+        assert interfaces == ["Onu1/0/1:1"]