fix(handlers): use correct route param name 'id' instead of 'libraryId' in processing issues

Both ListProcessingIssues and GetProcessingIssueStats were reading the
URL parameter 'libraryId', but the routes in internal/router/library.go
define the param as ':id'. This caused both endpoints to always fail with
an invalid library ID error since c.Param('libraryId') returns an empty
string that can't be parsed as a UUID.

internal/handlers/processing_issues.go

@@ -39,7 +39,7 @@ type ProcessingIssueStats struct {
 
 // ListProcessingIssues returns all processing issues for a library
 func (h *ProcessingIssuesHandler) ListProcessingIssues(c *echo.Context) error {
-	libraryID, err := uuid.Parse(c.Param("libraryId"))
+	libraryID, err := uuid.Parse(c.Param("id"))
 	if err != nil {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid library ID"})
 	}
@@ -73,7 +73,7 @@ func (h *ProcessingIssuesHandler) ListProcessingIssues(c *echo.Context) error {
 
 // GetProcessingIssueStats returns statistics about processing issues
 func (h *ProcessingIssuesHandler) GetProcessingIssueStats(c *echo.Context) error {
-	libraryID, err := uuid.Parse(c.Param("libraryId"))
+	libraryID, err := uuid.Parse(c.Param("id"))
 	if err != nil {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid library ID"})
 	}