feat(perf): AI 分析报告资源使用分析四维度增强（Java 进程 + MySQL）

- 资源使用分析扩展为四维度：执行机整体 / 目标机整体 / Java 进程 / MySQL
- 新增 _extract_java_process_stats / _extract_mysql_stats / _fmt_num 辅助方法
- Chapter 四重写为 4 小节，瓶颈表新增 Java 进程与 MySQL 条目，建议表同步
- 更新 LLM Prompt 第四章要求四维度分析，资源表头改 [资源,指标,值,状态]
- 修复 _rule_based_analysis 中 exec_cpu_avg / exec_cpu_max 未定义问题（上一轮遗留）
- 测试新增 4 个资源维度用例，共 20 passed，全量 295 passed
Co-Authored-By: Claude <noreply@anthropic.com>

backend/tests/test_performance_ai_service.py

@@ -211,6 +211,71 @@ class TestSnapshotSummary:
         assert str(summary).count("elapsed") == 4
 
 
+# ==================== 资源四维度提取测试 ====================
+
+class TestResourceDimensionExtraction:
+    """资源分析四维度：执行机整体 / 目标机整体 / Java 进程 / MySQL"""
+
+    TARGET = {
+        "host": "192.168.5.44",
+        "stats": {"avgCpuPercent": 85.0, "maxCpuPercent": 95.0, "avgMemPercent": 55.0, "maxMemPercent": 65.0},
+        "javaProcessStats": [
+            {"processName": "platform-app", "avgCpuPercent": 82.0, "maxCpuPercent": 95.0,
+             "avgMemPercent": 40.0, "maxMemPercent": 45.0, "avgRssMb": 1500.0, "maxRssMb": 1800.0}
+        ],
+        "mysql": {"available": True, "container": "umysql", "threadsConnected": 120, "threadsRunning": 8,
+                  "maxUsedConnections": 150, "maxConnections": 300, "slowQueries": 35, "bufferPoolHitRate": 97.5,
+                  "questions": 100000, "queries": 400000, "bytesReceivedMb": 12.0, "bytesSentMb": 88.0},
+    }
+
+    def test_java_process_stats_extraction(self):
+        svc = PerformanceAiService()
+        procs = svc._extract_java_process_stats(self.TARGET)
+        assert len(procs) == 1
+        assert procs[0]["processName"] == "platform-app"
+        assert procs[0]["avgCpuPercent"] == 82.0
+        assert svc._extract_java_process_stats(None) == []
+        assert svc._extract_java_process_stats({"stats": {}}) == []
+
+    def test_mysql_stats_extraction(self):
+        svc = PerformanceAiService()
+        mysql = svc._extract_mysql_stats(self.TARGET)
+        assert mysql["available"] is True
+        assert mysql["slowQueries"] == 35
+        assert mysql["bufferPoolHitRate"] == 97.5
+        # 未采集或 available=False 时返回空
+        assert svc._extract_mysql_stats(None) == {}
+        assert svc._extract_mysql_stats({"mysql": {"available": False, "slowQueries": 1}}) == {}
+
+    def test_rule_analysis_covers_four_dimensions(self):
+        """规则分析文档含 执行机 / 目标机 / Java / MySQL 四维度"""
+        svc = PerformanceAiService()
+        data = _make_report_data(
+            resource_summary={"stats": {"avgCpuPercent": 45.0, "maxCpuPercent": 70.0,
+                                        "avgMemPercent": 60.0, "maxMemPercent": 75.0}},
+            target_resource_summary=self.TARGET,
+        )
+        result = svc.analyze_single(data)
+        html = result["document_html"]
+        assert "执行机" in html
+        assert "目标机" in html
+        assert "Java 进程" in html
+        assert "MySQL" in html
+        # 高 CPU 目标机 + Java 进程 + 慢查询/命中率 均进入瓶颈
+        locs = [b["location"] for b in result["bottlenecks"]]
+        assert any("目标机" in l for l in locs)
+        assert any("Java 进程" in l for l in locs)
+        assert any("MySQL" in l for l in locs)
+
+    def test_rule_analysis_no_resource_data(self):
+        """无资源数据时不虚构，标注未采集"""
+        svc = PerformanceAiService()
+        data = _make_report_data(resource_summary={}, target_resource_summary={})
+        result = svc.analyze_single(data)
+        html = result["document_html"]
+        assert "未采集" in html or "无资源监控数据" in html or "无数据" in html
+
+
 # ==================== 文档规范化测试 ====================
 
 class TestNormalizeDocumentResult: