fix(tests): correct input validation tests for processing issues endpoints

Three issues fixed in processing_issues_test.go:

- Empty UUID: handler returns 400 (uuid.Parse rejects empty string), not 404.
  Fix expectedStatus in both List and Stats validation tests.
- Path traversal: raw '../../' in URL creates extra path segments that don't
  match the route. Use url.PathEscape so the string is treated as a single
  path parameter, letting the handler reject it with 400.
- SQL injection: raw special characters (semicolons, quotes) caused
  httptest.NewRequest to panic. url.PathEscape prevents the panic and the
  handler rejects the decoded value via uuid.Parse.
- Remove unsupported 'audiobooks' library type from
  TestProcessingIssuesDifferentLibraryTypes (only ebooks/comics/manga exist
  in the database schema).

cmd/server/tests/processing_issues_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -108,8 +109,8 @@ func TestProcessingIssuesListInputValidation(t *testing.T) {
 		{
 			name:           "Empty UUID",
 			libraryID:      "",
-			expectedStatus: http.StatusNotFound,
-			description:    "Should return 404 for empty ID",
+			expectedStatus: http.StatusBadRequest,
+			description:    "Should return 400 for empty ID",
 		},
 		{
 			name:           "UUID with extra path traversal",
@@ -139,7 +140,7 @@ func TestProcessingIssuesListInputValidation(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			req := httptest.NewRequest("GET", "/api/libraries/"+tc.libraryID+"/issues/list", nil)
+			req := httptest.NewRequest("GET", "/api/libraries/"+url.PathEscape(tc.libraryID)+"/issues/list", nil)
 			req.Header.Set("Authorization", "Bearer "+token)
 			rec := httptest.NewRecorder()
 
@@ -284,8 +285,8 @@ func TestProcessingIssueStatsInputValidation(t *testing.T) {
 		{
 			name:           "Empty UUID",
 			libraryID:      "",
-			expectedStatus: http.StatusNotFound,
-			description:    "Should return 404 for empty ID",
+			expectedStatus: http.StatusBadRequest,
+			description:    "Should return 400 for empty ID",
 		},
 		{
 			name:           "UUID with extra path traversal",
@@ -315,7 +316,7 @@ func TestProcessingIssueStatsInputValidation(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			req := httptest.NewRequest("GET", "/api/libraries/"+tc.libraryID+"/issues/stats", nil)
+			req := httptest.NewRequest("GET", "/api/libraries/"+url.PathEscape(tc.libraryID)+"/issues/stats", nil)
 			req.Header.Set("Authorization", "Bearer "+token)
 			rec := httptest.NewRecorder()
 
@@ -426,7 +427,6 @@ func TestProcessingIssuesDifferentLibraryTypes(t *testing.T) {
 		{"Ebooks library", "ebooks"},
 		{"Comics library", "comics"},
 		{"Manga library", "manga"},
-		{"Audiobooks library", "audiobooks"},
 	}
 
 	for _, lt := range libraryTypes {