重构：清理项目结构和完善文档

- 添加完整的 DOCS.md 文档（1376 行）
- 更新 README.md，增强项目说明
- 清理临时示例和测试数据
- 删除诊断工具（已完成测试）
- 为 webui 示例准备测试数据
- 优化 .gitignore 配置
- 增强 Query 和 Schema 功能
- 改进 SSTable 编码处理

examples/webui/data/logs/CURRENT

@@ -0,0 +1 @@
+MANIFEST-000001

examples/webui/data/logs/schema.json

@@ -0,0 +1,38 @@
+{
+  "version": 1,
+  "timestamp": 1760073184,
+  "checksum": "3ebde7026b498f38e4dd85058c995fff4a1a51bdb5a1254ead9a7e89030b1b76",
+  "schema": {
+    "Name": "logs",
+    "Fields": [
+      {
+        "Name": "group",
+        "Type": 13,
+        "Indexed": true,
+        "Nullable": false,
+        "Comment": "Log group (A-E)"
+      },
+      {
+        "Name": "timestamp",
+        "Type": 13,
+        "Indexed": false,
+        "Nullable": false,
+        "Comment": "Timestamp"
+      },
+      {
+        "Name": "data",
+        "Type": 13,
+        "Indexed": false,
+        "Nullable": false,
+        "Comment": "Random data"
+      },
+      {
+        "Name": "size_bytes",
+        "Type": 5,
+        "Indexed": false,
+        "Nullable": false,
+        "Comment": "Data size in bytes"
+      }
+    ]
+  }
+}

examples/webui/data/logs/wal/CURRENT

@@ -0,0 +1 @@
+151