Add Transmission/NZBGet and per-client paths and much more

Extend multi-download-client support to include Transmission and NZBGet and introduce per-client custom download paths. Adds protocol mapping and new client types, Transmission/NZBGet integration services, API CRUD and validation changes, UI components/modal updates and live path previews, and manager routing by protocol. Includes DB migrations (download_path on download_history, interactive_search_access on users), schema updates, and related processor/service fixes and tests to ensure backward compatibility and proper path resolution.

src/lib/utils/indexer-grouping.ts

@@ -5,6 +5,7 @@
  * Groups indexers by their category configuration to minimize API calls.
  * Indexers with identical categories are grouped together for a single search.
  * Supports separate audiobook and ebook category configurations per indexer.
+ * Indexers with no categories for a given type are skipped (effectively disabled).
  */
 
 export type CategoryType = 'audiobook' | 'ebook';
@@ -25,22 +26,33 @@ export interface IndexerGroup {
   indexers: IndexerConfig[];
 }
 
+export interface GroupingResult {
+  groups: IndexerGroup[];
+  skippedIndexers: IndexerConfig[]; // Indexers skipped due to no categories for the type
+}
+
 /**
  * Gets the appropriate categories from an indexer based on the category type.
  *
+ * Returns empty array when the field is explicitly set to [] (user disabled this type).
+ * Falls back to defaults only when the field is undefined/missing (legacy configs).
+ *
  * @param indexer - The indexer configuration
  * @param type - The category type ('audiobook' or 'ebook')
- * @returns Array of category IDs
+ * @returns Array of category IDs (empty = disabled for this type)
  */
 export function getCategoriesForType(indexer: IndexerConfig, type: CategoryType): number[] {
   if (type === 'ebook') {
-    return indexer.ebookCategories && indexer.ebookCategories.length > 0
-      ? indexer.ebookCategories
-      : [7020]; // Default ebook category
+    // Field exists (even if empty) — respect it
+    if (Array.isArray(indexer.ebookCategories)) {
+      return indexer.ebookCategories;
+    }
+    // Field missing — legacy config, use default
+    return [7020];
   }
 
-  // Audiobook - check new field first, then legacy field
-  if (indexer.audiobookCategories && indexer.audiobookCategories.length > 0) {
+  // Audiobook — check new field first, then legacy field
+  if (Array.isArray(indexer.audiobookCategories)) {
     return indexer.audiobookCategories;
   }
   if (indexer.categories && indexer.categories.length > 0) {
@@ -52,57 +64,49 @@ export function getCategoriesForType(indexer: IndexerConfig, type: CategoryType)
 /**
  * Groups indexers by their category configuration.
  * Indexers with identical category arrays are grouped together.
+ * Indexers with no categories for the specified type are skipped.
  *
  * @param indexers - Array of indexer configurations
  * @param type - The category type to group by ('audiobook' or 'ebook')
- * @returns Array of groups, each containing indexers with matching categories
+ * @returns GroupingResult with groups and skipped indexers
  *
  * @example
  * const indexers = [
  *   { id: 1, audiobookCategories: [3030], ebookCategories: [7020] },
- *   { id: 2, audiobookCategories: [3030], ebookCategories: [7020] },
+ *   { id: 2, audiobookCategories: [3030], ebookCategories: [] },
  *   { id: 3, audiobookCategories: [3030, 3010], ebookCategories: [7020] },
  * ];
  *
- * const audiobookGroups = groupIndexersByCategories(indexers, 'audiobook');
- * // Result:
- * // [
- * //   { categories: [3030], indexerIds: [1, 2], indexers: [...] },
- * //   { categories: [3030, 3010], indexerIds: [3], indexers: [...] }
- * // ]
- *
- * const ebookGroups = groupIndexersByCategories(indexers, 'ebook');
- * // Result:
- * // [
- * //   { categories: [7020], indexerIds: [1, 2, 3], indexers: [...] }
- * // ]
+ * const result = groupIndexersByCategories(indexers, 'ebook');
+ * // result.groups: [{ categories: [7020], indexerIds: [1, 3], indexers: [...] }]
+ * // result.skippedIndexers: [{ id: 2, ... }]  (no ebook categories)
  */
 export function groupIndexersByCategories(
   indexers: IndexerConfig[],
   type: CategoryType = 'audiobook'
-): IndexerGroup[] {
-  // Map to track unique category combinations
-  // Key: sorted category IDs as string (e.g., "3030,3010")
-  // Value: array of indexers with those categories
+): GroupingResult {
   const groupMap = new Map<string, IndexerConfig[]>();
+  const skippedIndexers: IndexerConfig[] = [];
 
   for (const indexer of indexers) {
-    // Get categories for the specified type
     const categories = getCategoriesForType(indexer, type);
 
+    // Skip indexers with no categories for this type (effectively disabled)
+    if (categories.length === 0) {
+      skippedIndexers.push(indexer);
+      continue;
+    }
+
     // Sort categories to ensure consistent grouping
-    // [3030, 3010] and [3010, 3030] should be the same group
     const sortedCategories = [...categories].sort((a, b) => a - b);
     const key = sortedCategories.join(',');
 
-    // Add indexer to group
     if (!groupMap.has(key)) {
       groupMap.set(key, []);
     }
     groupMap.get(key)!.push(indexer);
   }
 
-  // Convert map to array of groups
   const groups: IndexerGroup[] = [];
   for (const [key, indexersInGroup] of groupMap.entries()) {
     const categories = key.split(',').map(Number);
@@ -115,7 +119,7 @@ export function groupIndexersByCategories(
     });
   }
 
-  return groups;
+  return { groups, skippedIndexers };
 }
 
 /**