fix: 模型思考模式配置 + Unicode 截断 + 审计修复 (13 files)

模型模式:
- 新增 LLMConfig/Source.ThinkingEnabled 配置，通过 ExtraBody
  控制 DeepSeek thinking mode，默认关闭
- SeedDefaults/ToConfig 读写 core.llm.thinking_enabled
- deepseek.lua 移除硬编码 temperature=0

Unicode 截断:
- truncateStr 改按 rune 计数，修复中文截断乱码

审计修复 (Critical):
- graph.go: defer rows.Close 在 for 循环 → 显式 Close (连接池泄漏)
- cli/openclaw/plugin.go: bare type assertion → comma-ok (panic)
- channel.go: payload["type"].(string) → comma-ok (panic)
- webui/handler.go: .(string) → fmt.Sprint (panic)
- agent.go: 添加 nil provider 错误返回

审计修复 (High):
- events/bus.go: copy handler slice under RLock (data race)
- webui/handler.go: SSE 通过 channel 串行化写入 (data race)
- timer/plugin.go: time.Sleep → select with stopCh (Stop 阻塞)
- provider.go: stream ch <- 添加 select ctx.Done (goroutine 泄漏)
- main.go: outputCh goroutine 添加 ctx.Done 退出路径

internal/plugins/timer/plugin.go

@@ -17,9 +17,10 @@ func init() {
 }
 
 type Plugin struct {
-	name string
-	mu   sync.Mutex
-	wg   sync.WaitGroup
+	name   string
+	mu     sync.Mutex
+	wg     sync.WaitGroup
+	stopCh chan struct{}
 }
 
 type timerTask struct {
@@ -31,7 +32,7 @@ type timerTask struct {
 }
 
 func New(name string) *Plugin {
-	return &Plugin{name: name}
+	return &Plugin{name: name, stopCh: make(chan struct{})}
 }
 
 func (p *Plugin) Name() string { return p.name }
@@ -75,9 +76,13 @@ func (p *Plugin) Start(s *sdk.PluginSDK) error {
 
 		go func() {
 			defer p.wg.Done()
-			time.Sleep(dur)
-			log.Printf("[timer] firing: %s (%s later)", message, dur)
-			s.InjectInterruptText("timer", "timer", fmt.Sprintf("timer: %s", message))
+			select {
+			case <-time.After(dur):
+				log.Printf("[timer] firing: %s (%s later)", message, dur)
+				s.InjectInterruptText("timer", "timer", fmt.Sprintf("timer: %s", message))
+			case <-p.stopCh:
+				log.Printf("[timer] cancelled: %s", message)
+			}
 		}()
 
 		doneAt := time.Now().Add(dur)
@@ -93,6 +98,7 @@ func (p *Plugin) Start(s *sdk.PluginSDK) error {
 }
 
 func (p *Plugin) Stop() error {
+	close(p.stopCh)
 	p.wg.Wait()
 	return nil
 }