feat(PROJ-44): ocr_status/ocr_chars in MailDetail + v1 API

GET /api/mails/{id} liefert jetzt ocr_status + ocr_chars fuer das GUI-
Badge und den konditionalen Download-Button. Die externe v1-API
(/api/v1/mails/{id}) bekommt zusaetzlich ocr_status, damit CRM-
Integrationen entscheiden koennen, ob ein OCR-Text-Pull lohnt.

internal/api/search_handlers.go

@@ -311,6 +311,15 @@ func (s *Server) handleGetMail(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	// PROJ-44: OCR status + extracted character count for the GUI badge and
+	// the conditional "OCR-Text herunterladen" button. Errors are swallowed
+	// silently so a missing ocr_chars column on an old DB does not break the
+	// detail view; defaults are returned by GetOCRMeta in that case.
+	ocrStatus, ocrChars, _ := s.store.GetOCRMeta(r.Context(), id)
+	if ocrStatus == "" {
+		ocrStatus = "pending"
+	}
+
 	writeJSON(w, http.StatusOK, map[string]interface{}{
 		"id":          id,
 		"from":        pm.From,
@@ -326,6 +335,8 @@ func (s *Server) handleGetMail(w http.ResponseWriter, r *http.Request) {
 		"verify_ok":   verifyOK,
 		"verified_at": verifiedAt,
 		"thread_id":   threadID,
+		"ocr_status":  ocrStatus,
+		"ocr_chars":   ocrChars,
 	})
 }