docs(lua): 添加 Lua 配置示例和示例脚本

- lua-example.yaml 展示完整 Lua 中间件配置
- examples/lua-scripts/ 包含 auth.lua、content.lua、log.lua 示例

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/config/lua-example.yaml

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+# Lua Middleware 示例配置
+# 此文件演示如何在 lolly 中配置 Lua 中间件
+
+server:
+  listen: ":8080"
+  name: "lua-demo"
+
+  # Lua 中间件配置
+  lua:
+    enabled: true
+
+    # 全局 Lua 引擎设置
+    global_settings:
+      max_concurrent_coroutines: 1000  # 最大并发协程数
+      coroutine_timeout: 30s           # 协程执行超时
+      code_cache_size: 1000            # 字节码缓存条目数
+      enable_file_watch: true          # 启用文件变更检测（热重载）
+      max_execution_time: 30s          # 单脚本最大执行时间
+
+    # 脚本配置列表
+    scripts:
+      # Access 阶段 - 认证检查
+      - path: "/etc/lolly/scripts/auth.lua"
+        phase: "access"
+        timeout: 10s
+        enabled: true
+
+      # Content 阶段 - 内容生成
+      - path: "/etc/lolly/scripts/content.lua"
+        phase: "content"
+        timeout: 30s
+        enabled: true
+
+      # Log 阶段 - 日志记录
+      - path: "/etc/lolly/scripts/log.lua"
+        phase: "log"
+        timeout: 5s
+        enabled: true
+
+  # 其他服务器配置
+  read_timeout: 30s
+  write_timeout: 30s
+  idle_timeout: 120s
+  max_conns_per_ip: 100
+  max_requests_per_conn: 1000
+
+# 性能配置
+performance:
+  goroutine_pool:
+    enabled: true
+    max_workers: 1000
+    min_workers: 100
+    idle_timeout: 60s
+
+# 日志配置
+logging:
+  format: "json"
+  access:
+    path: "/var/log/lolly/access.log"
+    format: "combined"
+  error:
+    path: "/var/log/lolly/error.log"
+    level: "info"

examples/lua-scripts/auth.lua

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+-- auth.lua - Access 阶段认证检查示例
+-- 此脚本演示如何在 access 阶段进行简单的 token 认证
+
+local auth_header = ngx.req.get_headers()["Authorization"]
+
+if not auth_header then
+    ngx.say("Missing Authorization header")
+    ngx.exit(401)
+end
+
+-- 验证 token (示例：简单的 token 检查)
+local token = auth_header
+if string.sub(token, 1, 7) ~= "Bearer " then
+    ngx.say("Invalid token format")
+    ngx.exit(401)
+end
+
+local actual_token = string.sub(token, 8)
+
+-- 这里可以连接数据库或调用认证服务验证 token
+-- 示例：简单的 token 比较
+if actual_token ~= "valid-token-123" then
+    ngx.say("Invalid token")
+    ngx.exit(403)
+end
+
+-- 认证成功，设置用户信息到上下文
+ngx.ctx.user_id = "user-123"
+ngx.ctx.auth_time = ngx.now()
+
+-- 继续处理请求

examples/lua-scripts/content.lua

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+-- content.lua - Content 阶段内容生成示例
+-- 此脚本演示如何在 content 阶段生成响应内容
+
+-- 检查是否有认证信息
+local user_id = ngx.ctx.user_id
+if not user_id then
+    -- 未认证，返回错误
+    ngx.say("Not authenticated")
+    ngx.exit(401)
+end
+
+-- 生成响应内容
+ngx.say("Hello, " .. user_id .. "!")
+ngx.say("Request processed at: " .. ngx.now())
+
+-- 设置响应头
+ngx.resp.set_header("X-User-Id", user_id)
+ngx.resp.set_header("X-Server", "lolly-lua")
+
+-- 可以根据请求路径返回不同内容
+local uri = ngx.var.uri
+if uri == "/api/status" then
+    ngx.say("Status: OK")
+end
+
+-- 正常完成处理
+ngx.exit(200)

examples/lua-scripts/log.lua

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+-- log.lua - Log 阶段日志记录示例
+-- 此脚本演示如何在 log 阶段记录请求信息
+
+local log_data = {
+    uri = ngx.var.uri,
+    method = ngx.req.get_method(),
+    status = ngx.resp.get_status(),
+    user_id = ngx.ctx.user_id or "anonymous",
+    auth_time = ngx.ctx.auth_time or 0,
+    duration = ngx.now() - ngx.ctx.start_time
+}
+
+-- 输出日志信息（实际应用中可写入文件或发送到日志服务）
+ngx.log(ngx.INFO, "Request completed: " ..
+    log_data.method .. " " ..
+    log_data.uri .. " " ..
+    "status=" .. log_data.status .. " " ..
+    "user=" .. log_data.user_id .. " " ..
+    "duration=" .. log_data.duration .. "s")
+
+-- 记录响应大小
+local response_size = #ngx.resp.get_headers()
+ngx.log(ngx.INFO, "Response headers count: " .. response_size)