fix(PROJ-44): IMAP+POP3 Live-Import triggert OCR-Worker

Bisher haben nur der SMTP-Pfad und der Boot-Backfill ocrWorker.Submit
gerufen. IMAP- und POP3-Importer riefen nur idx.IndexSync auf —
neue Mails blieben dadurch dauerhaft in ocr_status='pending' (auf 132
44 Tage 54 Mails so haengen geblieben).

Fix: Importer-Strukturen bekommen einen optionalen ocrSubmit-Callback,
in main.go via SetOCRSubmit gehookt. Kein Import von internal/ocr in
die Importer-Packages -> kein Risiko von Cycles. Submit ist
non-blocking; bei Mails ohne Attachments markiert der Worker selbst
'skipped'.

internal/pop3/importer.go

@@ -19,6 +19,8 @@ type Importer struct {
 	idx       index.Indexer
 	logger    *slog.Logger
 	TenantID  *int64 // optional tenant assignment for stored mails
+	// PROJ-44: optional OCR enqueue hook, wired from main.go.
+	ocrSubmit func(mailID string, tenantID *int64)
 }
 
 // NewImporter creates a new Importer wired to the storage and index backends.
@@ -31,6 +33,12 @@ func NewImporter(store *Store, mailStore *storage.Store, idx index.Indexer, logg
 	}
 }
 
+// SetOCRSubmit installs a non-blocking callback that enqueues a mail for
+// OCR processing. See imap.Importer.SetOCRSubmit for rationale (PROJ-44).
+func (imp *Importer) SetOCRSubmit(fn func(mailID string, tenantID *int64)) {
+	imp.ocrSubmit = fn
+}
+
 // Run performs a full POP3 import for the given account. It is designed to be
 // called as a goroutine: go imp.Run(context.Background(), accountID)
 func (imp *Importer) Run(ctx context.Context, accountID int64) {
@@ -166,5 +174,10 @@ func (imp *Importer) storeAndIndex(raw []byte, log *slog.Logger) error {
 		// Non-fatal: mail is stored, just not searchable yet
 	}
 
+	// PROJ-44: enqueue OCR job for any mail with attachments.
+	if imp.ocrSubmit != nil && len(pm.Attachments) > 0 {
+		imp.ocrSubmit(id, imp.TenantID)
+	}
+
 	return nil
 }