feat(PROJ-35): OCR & Anhang-Volltext-Indexierung

Asynchrone OCR fuer PDF- und Bild-Anhaenge via tesseract + poppler-utils.
Extrahierter Text wird in Manticore (attachment_text) gespeichert und ist
ueber die normale Volltextsuche auffindbar.

- internal/ocr: ExtractText + Worker (queue + drain)
- internal/storage/ocr.go: SetOCRStatus, OCREnabled, GetMailsByOCRStatus
- emails.ocr_status (pending|done|failed|skipped|disabled)
- tenants.ocr_enabled (Default TRUE, opt-out)
- Manticore: attachment_text-Feld + UpdateAttachmentText
- Boot-resume: pending Jobs nach Restart automatisch in die Queue
- CLI: archivmail ocr-reprocess --tenant N --status pending|failed|all
- update.sh: tesseract-ocr + poppler-utils optional installieren

internal/index/index.go

@@ -7,16 +7,17 @@ import (
 
 // MailDocument is the indexed representation of a stored email.
 type MailDocument struct {
-	ID            string
-	From          string
-	To            string
-	Subject       string
-	Body          string
-	AttachNames   string
-	HasAttachment bool
-	Date          time.Time
-	Size          int64
-	TenantID      *int64 // nil = global / superadmin context
+	ID             string
+	From           string
+	To             string
+	Subject        string
+	Body           string
+	AttachNames    string
+	AttachmentText string // PROJ-35: OCR-extracted text from PDF/image attachments
+	HasAttachment  bool
+	Date           time.Time
+	Size           int64
+	TenantID       *int64 // nil = global / superadmin context
 }
 
 // SearchRequest specifies search parameters.
@@ -53,6 +54,15 @@ type Indexer interface {
 	Close() error
 }
 
+// AttachmentTextUpdater is implemented by indexers that support partial
+// updates of the OCR-extracted attachment text. Optional add-on to Indexer:
+// callers should type-assert and degrade gracefully if not supported.
+//
+// PROJ-35: Manticore implements this; legacy Xapian does not.
+type AttachmentTextUpdater interface {
+	UpdateAttachmentText(mailID, text string) error
+}
+
 // TenantIndexer manages per-tenant Indexer instances.
 // Implemented by ManticoreTenantManager (primary) and TenantIndexManager (legacy Xapian).
 type TenantIndexer interface {