#5: F2 sub-project 2 - IMAP SEARCH, EXPUNGE, COPY, MOVE

Adds the second F2 sub-project on top of the merged IMAP core: full
SEARCH criteria matching (flags, dates, size, headers, body/text,
NOT/OR), EXPUNGE (soft-delete via expunged_at), COPY, and MOVE (RFC
6851, advertised via CapMove/CapUIDPlus). Verified end-to-end with a
real go-imap/v2 client against embedded Postgres.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

services/protocols/internal/application/port/expunge_repository.go

@@ -0,0 +1,16 @@
+package port
+
+import "context"
+
+// ExpungeRepository permanently marks messages as expunged (soft delete -
+// email_messages.expunged_at is set, never a hard DELETE). Blob ref_count
+// is deliberately untouched here; physical blob garbage collection is a
+// separate future concern.
+type ExpungeRepository interface {
+	// Expunge marks each message identified by (folderID, uid) in uids as
+	// expunged, decrementing the folder's total_count (and unread_count for
+	// any message that lacked \Seen). The caller is responsible for having
+	// already determined that every UID in uids actually carries \Deleted -
+	// this method does not re-check that itself.
+	Expunge(ctx context.Context, folderID string, uids []uint32) error
+}