activity: global feed, per-case log, sidebar section, today UX

- migration 009: target_type, target_id, target_path columns
- new Event fields: TargetType, TargetID, TargetPath
- ListActivityFeed (paginated global), ListActivityByNode (per-case)
- all Record() callsites pass target info
- frontend: Активность sidebar section with chronological feed
- per-case Активность tab with real data (was placeholder)
- today events: clickable, target-type badges, event counts

internal/core/storage/migrations_009.sql.go

@@ -0,0 +1,8 @@
+package storage
+
+// migration009 — add target_type, target_id, target_path to activity_events.
+const migration009 = `
+ALTER TABLE activity_events ADD COLUMN target_type TEXT;
+ALTER TABLE activity_events ADD COLUMN target_id TEXT;
+ALTER TABLE activity_events ADD COLUMN target_path TEXT;
+`

internal/core/storage/storage.go

@@ -65,6 +65,7 @@ var migrationFiles = map[int]string{
 	6: migration006,
 	// 7: migration007 (FTS5) — created lazily by search.Rebuild()
 	8: migration008,
+	9: migration009,
 }
 
 func (db *DB) runInitialSchema() error {