Final cleanup: Update remaining comments and variable names

Changes:
- Update comments: "Bookmann UUID" → "Bookhoard UUID"
- Rename sidecar struct field: Bookmann → Bookhoard
- Update type names: SidecarBookmannConfig → SidecarBookhoardConfig
- Fix test database name in queue_test.go
- Fix uppercase env var examples in KOBO_SETUP.md

Internal Go variable names (BookmannUuid, bookmannUUID) left unchanged
as they're implementation details that don't affect functionality.

Part of project rename to Bookhoard.

internal/handlers/kobo.go

@@ -25,13 +25,13 @@ func NewKoboHandler(db *database.Queries, connManager *wsync.ConnectionManager)
 	return &KoboHandler{db: db, connManager: connManager}
 }
 
-// mapContentIdToBookhoardUUID maps Kobo ContentId to Bookmann UUID with multiple fallback strategies
+// mapContentIdToBookhoardUUID maps Kobo ContentId to Bookhoard UUID with multiple fallback strategies
 // Phase 6: Enhanced Kobo Sync - ContentId Mapping Logic
 func (h *KoboHandler) mapContentIdToBookhoardUUID(ctx echo.Context, contentId string, deviceID uuid.UUID) (uuid.UUID, error, string) {
 	// Step 1: Try direct ContentId lookup in device_catalogs table
 	catalog, err := h.db.GetDeviceCatalogByKoboContentId(ctx.Request().Context(), contentId)
 	if err == nil && catalog.ID.Valid {
-		// Found! Use canonical Bookmann UUID
+		// Found! Use canonical Bookhoard UUID
 		return uuid.UUID(catalog.BookmannUuid.Bytes), nil, "catalog_match"
 	}
 
@@ -79,7 +79,7 @@ func (h *KoboHandler) mapContentIdToBookhoardUUID(ctx echo.Context, contentId st
 	return uuid.Nil, fmt.Errorf("unlinked book: ContentId %s not found", contentId), "unlinked"
 }
 
-// mapBookhoardUUIDToKoboContentId maps Bookmann UUID to Kobo ContentId
+// mapBookhoardUUIDToKoboContentId maps Bookhoard UUID to Kobo ContentId
 // Creates new entry in device_catalogs if not exists
 func (h *KoboHandler) mapBookhoardUUIDToKoboContentId(c echo.Context, bookmannUUID uuid.UUID, deviceID uuid.UUID) (string, error) {
 	// Check if catalog entry already exists