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.

tests/utils/permissions.test.ts

@@ -0,0 +1,31 @@
+/**
+ * Utility: Permission Resolution Tests
+ * Documentation: documentation/admin-dashboard.md
+ */
+
+import { describe, expect, it } from 'vitest';
+import { resolvePermission } from '@/lib/utils/permissions';
+
+describe('resolvePermission', () => {
+  it('always grants permission for admins regardless of other settings', () => {
+    expect(resolvePermission('admin', null, false)).toBe(true);
+    expect(resolvePermission('admin', false, false)).toBe(true);
+    expect(resolvePermission('admin', true, false)).toBe(true);
+    expect(resolvePermission('admin', null, true)).toBe(true);
+  });
+
+  it('uses per-user setting when explicitly true', () => {
+    expect(resolvePermission('user', true, false)).toBe(true);
+    expect(resolvePermission('user', true, true)).toBe(true);
+  });
+
+  it('uses per-user setting when explicitly false', () => {
+    expect(resolvePermission('user', false, true)).toBe(false);
+    expect(resolvePermission('user', false, false)).toBe(false);
+  });
+
+  it('falls back to global setting when per-user is null', () => {
+    expect(resolvePermission('user', null, true)).toBe(true);
+    expect(resolvePermission('user', null, false)).toBe(false);
+  });
+});