feat(backthink): 自主思考 P2——结构化推送决策+渠道选择(design/20)

- proactive.go(新): parseProactive 从结论解析 [我决定:push|no_push][渠道:...]<正文>;
  兼容大小写/全半角冒号; 无标记回退(无/nothing=不推); 畸形/孤标记 fail-safe 不推
- context.go: guidancePrompt 引导结构化结尾+保留P1温暖引导
- push.go: PushRequest{Message,ChannelHint}; Pusher.Push 路由(auto→active优先/IM兜底,
  web→仅active, im→仅IM, 具体平台→IM+platform打标+缺IM回退默认记detail); buildProactiveMessage
- backthink.go: think() 用 parseProactive→ShouldPush=push&&disturbAllowed(不再被tr.Import卡死)
- decide.go: disturbAllowed(asleep/working/quiet 硬性不打扰门) 取代旧import门(保留旧Decide兼容)
- 测试: parseProactive 6组+think端到端(真实pusher:kook→IM/无标记→active/no_push→不推/睡眠→门拦截)
   +buildProactiveMessage+具体平台无IM回退; 后端 build/vet/test 全绿
- 注: 生产 Active/IM sink 未注入 wire.go backthink.Deps(另一步); 多平台IM受单IMAdapter接口限制

internal/services/backthink/push_test.go

@@ -14,7 +14,7 @@ func TestPusher_ActiveFirst(t *testing.T) {
 	im := &mockIMAdapter{}
 	p := newPusher(active, im, &mockGate{allow: true}, discardLog())
 
-	res := p.Push(context.Background(), adapter.UnifiedMessage{})
+	res := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if !res.Pushed {
 		t.Fatalf("Pushed = false, want true")
@@ -36,7 +36,7 @@ func TestPusher_IMFallback_NoActive(t *testing.T) {
 	im := &mockIMAdapter{}
 	p := newPusher(active, im, &mockGate{allow: true}, discardLog())
 
-	res := p.Push(context.Background(), adapter.UnifiedMessage{})
+	res := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if !res.Pushed {
 		t.Fatalf("Pushed = false, want true")
@@ -55,7 +55,7 @@ func TestPusher_IMFallback_ActiveError(t *testing.T) {
 	im := &mockIMAdapter{}
 	p := newPusher(active, im, &mockGate{allow: true}, discardLog())
 
-	res := p.Push(context.Background(), adapter.UnifiedMessage{})
+	res := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if !res.Pushed {
 		t.Fatalf("Pushed = false, want true")
@@ -72,7 +72,7 @@ func TestPusher_NoTarget_Skipped(t *testing.T) {
 	t.Parallel()
 	p := newPusher(nil, nil, &mockGate{allow: true}, discardLog())
 
-	res := p.Push(context.Background(), adapter.UnifiedMessage{})
+	res := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if res.Pushed {
 		t.Fatalf("Pushed = true, want false")
@@ -88,7 +88,7 @@ func TestPusher_GateDenied(t *testing.T) {
 	im := &mockIMAdapter{}
 	p := newPusher(active, im, &mockGate{allow: false}, discardLog())
 
-	res := p.Push(context.Background(), adapter.UnifiedMessage{})
+	res := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if res.Pushed {
 		t.Fatalf("Pushed = true, want false")
@@ -108,7 +108,7 @@ func TestPusher_CancelledContext_Denied(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	res := p.Push(ctx, adapter.UnifiedMessage{})
+	res := p.Push(ctx, PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if res.Pushed {
 		t.Fatalf("Pushed = true, want false")
@@ -128,9 +128,9 @@ func TestPusher_RateLimit(t *testing.T) {
 	active := &mockActive{n: 1}
 	p := newPusher(active, nil, newRateGate(1, time.Minute, discardLog()), discardLog())
 
-	first := p.Push(context.Background(), adapter.UnifiedMessage{})
-	second := p.Push(context.Background(), adapter.UnifiedMessage{})
-	third := p.Push(context.Background(), adapter.UnifiedMessage{})
+	first := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
+	second := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
+	third := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{}})
 
 	if !first.Pushed || first.Route != RouteActiveClient {
 		t.Fatalf("first push = %+v, want active_client pushed", first)