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)

go.mod

@@ -26,6 +26,7 @@ require (
 	github.com/larksuite/oapi-sdk-go/v3 v3.5.3
 	github.com/mailgun/mailgun-go/v5 v5.14.0
 	github.com/memohai/acgo v0.0.0-20260221232113-babac0d6acd7
+	github.com/memohai/dingtalk-stream-sdk-go v0.0.0-20260405113102-87e23096b978
 	github.com/memohai/twilight-ai v0.3.4-0.20260402160505-00db38ee4442
 	github.com/modelcontextprotocol/go-sdk v1.4.1
 	github.com/opencontainers/image-spec v1.1.1