feat: Agent 任务名与对话标题双能力自动生成

新增 task_auto_title_enabled / chat_auto_title_enabled（默认关）、
共享 GenerateAutoTitle、spawn_task 同步写 name、对话首条先截断再异步 AI，
设置页「自动标题」双 Switch。closes #55

agent/auto_title_test.go

@@ -0,0 +1,51 @@
+package agent
+
+import (
+	"context"
+	"errors"
+	"iter"
+	"strings"
+	"testing"
+
+	"github.com/Autumn-27/norma/llm"
+)
+
+type autoTitleProvider struct {
+	reply string
+	err   error
+	req   llm.CompletionRequest
+}
+
+func (p *autoTitleProvider) Complete(_ context.Context, req llm.CompletionRequest) (llm.Message, string, llm.Usage, error) {
+	p.req = req
+	if p.err != nil {
+		return llm.Message{}, "", llm.Usage{}, p.err
+	}
+	return llm.Message{Role: llm.RoleAssistant, Content: []llm.ContentBlock{llm.TextBlock(p.reply)}}, "stop", llm.Usage{}, nil
+}
+
+func (p *autoTitleProvider) Stream(context.Context, llm.CompletionRequest) iter.Seq2[llm.StreamEvent, error] {
+	return func(func(llm.StreamEvent, error) bool) {}
+}
+
+func TestGenerateAutoTitleCleansResponse(t *testing.T) {
+	long := strings.Repeat("很长", 30)
+	p := &autoTitleProvider{reply: "\n\"标题：" + long + "\"\n第二行"}
+	got, err := GenerateAutoTitle(t.Context(), p, "用户希望整理项目设置")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.ContainsAny(got, "\r\n") || strings.Contains(got, "标题：") || strings.HasPrefix(got, "\"") || len([]rune(got)) > 40 {
+		t.Fatalf("unclean title %q", got)
+	}
+	if p.req.Thinking != "disabled" || p.req.MaxTokens != 96 || len(p.req.Tools) != 0 {
+		t.Fatalf("request options: %+v", p.req)
+	}
+}
+
+func TestGenerateAutoTitleProviderError(t *testing.T) {
+	_, err := GenerateAutoTitle(t.Context(), &autoTitleProvider{err: errors.New("boom")}, "内容")
+	if err == nil {
+		t.Fatal("expected provider error")
+	}
+}