refactor: content-addressed assets, cross-channel multimodal, infra simplification (#63)

* refactor(attachment): multimodal attachment refactor with snapshot schema and storage layer

- Add snapshot schema migration (0008) and update init/versions/snapshots
- Add internal/attachment and internal/channel normalize for unified attachment handling
- Move containerfs provider from internal/media to internal/storage
- Update agent types, channel adapters (Telegram/Feishu), inbound and handlers
- Add containerd snapshot lineage and local_channel tests
- Regenerate sqlc, swagger and SDK

* refactor(media): content-addressed asset system with unified naming

- Replace asset_id foreign key with content_hash as sole identifier
  for bot_history_message_assets (pure soft-link model)
- Remove mime, size_bytes, storage_key from DB; derive at read time
  via media.Resolve from actual storage
- Merge migrations 0008/0009 into single 0008; keep 0001 as canonical schema
- Add Docker initdb script for deterministic migration execution order
- Fix cross-channel real-time image display (Telegram → WebUI SSE)
- Fix message disappearing on refresh (null assets fallback)
- Fix file icon instead of image preview (mime derivation from storage)
- Unify AssetID → ContentHash naming across Go, Agent, and Frontend
- Change storage key prefix from 4-char to 2-char for directory sharding
- Add server-entrypoint.sh for Docker deployment migration handling

* refactor(infra): embedded migrations, Docker simplification, and config consolidation

- Embed SQL migrations into Go binary, removing shell-based migration scripts
- Consolidate config files into conf/ directory (app.example.toml, app.docker.toml, app.dev.toml)
- Simplify Docker setup: remove initdb.d scripts, streamline nginx config and entrypoint
- Remove legacy CLI, feishu-echo commands, and obsolete incremental migration files
- Update install script and docs to require sudo for one-click install
- Add mise tasks for dev environment orchestration

* chore: recover migrations

---------

Co-authored-by: Acbox <acbox0328@gmail.com>

internal/message/types.go

@@ -7,18 +7,14 @@ import (
 )
 
 // MessageAsset carries media asset metadata attached to a message.
+// ContentHash is the content-addressed identifier for the media file.
 type MessageAsset struct {
-	AssetID      string `json:"asset_id"`
-	Role         string `json:"role"`
-	Ordinal      int    `json:"ordinal"`
-	MediaType    string `json:"media_type"`
-	Mime         string `json:"mime"`
-	SizeBytes    int64  `json:"size_bytes"`
-	StorageKey   string `json:"storage_key"`
-	OriginalName string `json:"original_name,omitempty"`
-	Width        int    `json:"width,omitempty"`
-	Height       int    `json:"height,omitempty"`
-	DurationMs   int64  `json:"duration_ms,omitempty"`
+	ContentHash string `json:"content_hash"`
+	Role        string `json:"role"`
+	Ordinal     int    `json:"ordinal"`
+	Mime        string `json:"mime"`
+	SizeBytes   int64  `json:"size_bytes"`
+	StorageKey  string `json:"storage_key"`
 }
 
 // Message represents a single persisted bot message.
@@ -42,10 +38,14 @@ type Message struct {
 }
 
 // AssetRef links a media asset to a persisted message.
+// ContentHash is the content-addressed identifier for the media file.
 type AssetRef struct {
-	AssetID string `json:"asset_id"`
-	Role    string `json:"role"`
-	Ordinal int    `json:"ordinal"`
+	ContentHash string `json:"content_hash"`
+	Role        string `json:"role"`
+	Ordinal     int    `json:"ordinal"`
+	Mime        string `json:"mime,omitempty"`
+	SizeBytes   int64  `json:"size_bytes,omitempty"`
+	StorageKey  string `json:"storage_key,omitempty"`
 }
 
 // PersistInput is the input for persisting a message.