fix(channel,attachment): channel quality refactor & attachment pipeline fixes (#349)

* feat(channel): add DingTalk channel adapter

- Add DingTalk channel adapter (`internal/channel/adapters/dingtalk/`) using dingtalk-stream-sdk-go, supporting inbound message receiving and outbound text/markdown reply
- Register DingTalk adapter in cmd/agent and cmd/memoh
- Add go.mod dependency: github.com/memohai/dingtalk-stream-sdk-go
- Add Dingtalk and Wecom SVG icons and Vue components to @memohai/icon
- Refactor existing icon components to remove redundant inline wrappers
- Add `channelTypeDisplayName` util for consistent channel label resolution
- Add DingTalk/WeCom i18n entries (en/zh) for types and typesShort
- Extend channel-icon, bot-channels, channel-settings-panel to support dingtalk/wecom
- Use channelTypeDisplayName in profile page to replace ad-hoc i18n lookup

* fix(channel,attachment): channel quality refactor & attachment pipeline fixes

Channel module:
- Fix RemoveAdapter not cleaning connectionMeta (stale status leak)
- Fix preparedAttachmentTypeFromMime misclassifying image/gif
- Fix sleepWithContext time.After goroutine/timer leak
- Export IsDataURL/IsHTTPURL/IsDataPath, dedup across packages
- Cache OutboundPolicy in managerOutboundStream to avoid repeated lookups
- Split OutboundAttachmentStore: extract ContainerAttachmentIngester interface
- Add ManagerOption funcs (WithInboundQueueSize, WithInboundWorkers, WithRefreshInterval)
- Add thread-safety docs on OutboundStream / managerOutboundStream
- Add debug logs on successful send/edit paths
- Expand outbound_prepare_test.go with 21 new cases
- Convert no-receiver adapter helpers to package-level funcs; drop unused params

DingTalk adapter:
- Implement AttachmentResolver: download inbound media via /v1.0/robot/messageFiles/download
- Fix pure-image inbound messages failing due to missing resolver

Attachment pipeline:
- Fix images invisible to LLM in pipeline (DCP) path: inject InlineImages into
  last user message when cfg.Query is empty
- Fix public_url fallback: skip direct URL-to-LLM when ContentHash is set,
  always prefer inlined persisted asset
- Inject path: carry ImageParts through agent.InjectMessage; inline persisted
  attachments in resolver inject goroutine so mid-stream images reach the model
- Fix ResolveMime for images: prefer content-sniffed MIME over platform-declared
  MIME (fixes Feishu sending image/png header for actual JPEG content → API 400)

internal/messaging/executor_test.go

@@ -2,9 +2,11 @@ package messaging
 
 import (
 	"context"
+	"io"
 	"testing"
 
 	"github.com/memohai/memoh/internal/channel"
+	"github.com/memohai/memoh/internal/media"
 )
 
 type testSender struct {
@@ -29,10 +31,26 @@ type testAssetResolver struct {
 	lastPath     string
 }
 
+func (*testAssetResolver) Stat(_ context.Context, _, _ string) (AssetMeta, error) {
+	return AssetMeta{}, context.Canceled
+}
+
 func (*testAssetResolver) GetByStorageKey(_ context.Context, _, _ string) (AssetMeta, error) {
 	return AssetMeta{}, context.Canceled
 }
 
+func (*testAssetResolver) Open(_ context.Context, _, _ string) (io.ReadCloser, media.Asset, error) {
+	return nil, media.Asset{}, context.Canceled
+}
+
+func (*testAssetResolver) Ingest(_ context.Context, _ media.IngestInput) (media.Asset, error) {
+	return media.Asset{}, context.Canceled
+}
+
+func (*testAssetResolver) AccessPath(asset media.Asset) string {
+	return "https://example.com/media/" + asset.ContentHash
+}
+
 func (r *testAssetResolver) IngestContainerFile(_ context.Context, _, containerPath string) (AssetMeta, error) {
 	r.ingestCalled++
 	r.lastPath = containerPath
@@ -164,7 +182,7 @@ func TestSendDirectPromotesDataPathAttachmentToContentHash(t *testing.T) {
 	if att.ContentHash != "hash_1" {
 		t.Fatalf("expected promoted content hash, got %q", att.ContentHash)
 	}
-	if att.URL != "" {
-		t.Fatalf("expected URL cleared after promotion, got %q", att.URL)
+	if att.URL != "https://example.com/media/hash_1" {
+		t.Fatalf("expected public access URL after promotion, got %q", att.URL)
 	}
 }