refactor(conflicts): one ConflictDetail builder for the three row shapes

ListConflicts, GetConflict, and the SSR media-detail active-conflict
lookup each hand-mapped their sqlc row (list-by-user, get-by-id,
list-by-media-item) into ConflictDetailResponse, triplicating the
optional resolution tail — including the silently-swallowed
ResolutionData unmarshal error, three times. NewConflictDetail is the
single mapper; a malformed resolution blob now logs instead of
vanishing.

Also extracts koreaderSyncEndpoints (the KOReader URL map duplicated
verbatim between token rotation and device approval; kobo's two URL
sets stay local because they deliberately differ).

Verified in the test-runner container (host conflict tests fail
environmentally on the container-only uploads path — baseline behavior).

internal/handlers/conflicts.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"log"
 	"net/http"
 	"time"
 
@@ -103,26 +104,10 @@ func (h *ConflictHandler) GetConflictsData(c *echo.Context) ([]ConflictDetailRes
 			continue
 		}
 
-		detail := ConflictDetailResponse{
-			ID:               uuid.UUID(conflict.ID.Bytes).String(),
-			MediaItemID:      uuid.UUID(conflict.MediaItemID.Bytes).String(),
-			MediaItemTitle:   conflict.Title,
-			ConflictType:     conflict.ConflictType,
-			ConflictData:     conflictData,
-			ResolutionStatus: conflict.ResolutionStatus.String,
-			CreatedAt:        conflict.CreatedAt.Time,
-		}
-
-		if conflict.ResolvedBy.Valid {
-			detail.ResolvedBy = uuid.UUID(conflict.ResolvedBy.Bytes).String()
-		}
-		if conflict.ResolvedAt.Valid {
-			detail.ResolvedAt = &conflict.ResolvedAt.Time
-		}
-		if conflict.ResolutionData != nil {
-			if err := json.Unmarshal(conflict.ResolutionData, &detail.ResolutionData); err == nil {
-			}
-		}
+		detail := NewConflictDetail(conflict.ID, conflict.MediaItemID,
+			conflict.Title, conflict.ConflictType, conflict.ResolutionStatus.String,
+			conflictData, conflict.CreatedAt, conflict.ResolvedAt, conflict.ResolvedBy,
+			conflict.ResolutionData)
 
 		response = append(response, detail)
 		if conflict.ResolutionStatus.String == "unresolved" {
@@ -133,6 +118,41 @@ func (h *ConflictHandler) GetConflictsData(c *echo.Context) ([]ConflictDetailRes
 	return response, len(response), unresolvedCount, nil
 }
 
+// NewConflictDetail maps any sync-conflict row shape (list-by-user,
+// get-by-id, list-by-media-item) to the wire detail. The resolution
+// tail is conditional exactly as before; a malformed resolution blob
+// now logs instead of vanishing silently.
+func NewConflictDetail(
+	id, mediaItemID pgtype.UUID,
+	title, conflictType, resolutionStatus string,
+	conflictData map[string]ConflictSourceData,
+	createdAt, resolvedAt pgtype.Timestamptz,
+	resolvedBy pgtype.UUID,
+	resolutionData []byte,
+) ConflictDetailResponse {
+	detail := ConflictDetailResponse{
+		ID:               uuid.UUID(id.Bytes).String(),
+		MediaItemID:      uuid.UUID(mediaItemID.Bytes).String(),
+		MediaItemTitle:   title,
+		ConflictType:     conflictType,
+		ConflictData:     conflictData,
+		ResolutionStatus: resolutionStatus,
+		CreatedAt:        createdAt.Time,
+	}
+	if resolvedBy.Valid {
+		detail.ResolvedBy = uuid.UUID(resolvedBy.Bytes).String()
+	}
+	if resolvedAt.Valid {
+		detail.ResolvedAt = &resolvedAt.Time
+	}
+	if resolutionData != nil {
+		if err := json.Unmarshal(resolutionData, &detail.ResolutionData); err != nil {
+			log.Printf("conflict %s: unparsable resolution data: %v", detail.ID, err)
+		}
+	}
+	return detail
+}
+
 func (h *ConflictHandler) ListConflicts(c *echo.Context) error {
 	conflicts, total, unresolved, err := h.GetConflictsData(c)
 	if err != nil {
@@ -177,26 +197,10 @@ func (h *ConflictHandler) GetConflict(c *echo.Context) error {
 		return echo.NewHTTPError(http.StatusInternalServerError, "failed to parse conflict data")
 	}
 
-	detail := ConflictDetailResponse{
-		ID:               uuid.UUID(conflict.ID.Bytes).String(),
-		MediaItemID:      uuid.UUID(conflict.MediaItemID.Bytes).String(),
-		MediaItemTitle:   mediaItem.Title,
-		ConflictType:     conflict.ConflictType,
-		ConflictData:     conflictData,
-		ResolutionStatus: conflict.ResolutionStatus.String,
-		CreatedAt:        conflict.CreatedAt.Time,
-	}
-
-	if conflict.ResolvedBy.Valid {
-		detail.ResolvedBy = uuid.UUID(conflict.ResolvedBy.Bytes).String()
-	}
-	if conflict.ResolvedAt.Valid {
-		detail.ResolvedAt = &conflict.ResolvedAt.Time
-	}
-	if conflict.ResolutionData != nil {
-		if err := json.Unmarshal(conflict.ResolutionData, &detail.ResolutionData); err == nil {
-		}
-	}
+	detail := NewConflictDetail(conflict.ID, conflict.MediaItemID,
+		mediaItem.Title, conflict.ConflictType, conflict.ResolutionStatus.String,
+		conflictData, conflict.CreatedAt, conflict.ResolvedAt, conflict.ResolvedBy,
+		conflict.ResolutionData)
 
 	return c.JSON(http.StatusOK, detail)
 }