Fix CI failures in NostrClient and SignerManager

- Export `resolveSignerCapabilities` from `SignerManager` and import in `NostrClient` to fix ReferenceError in `sendDirectMessage`.
- Initialize `RelayBatchFetcher` in `NostrClient` constructor to fix TypeError in `fetchListIncrementally`.
- Implement `registerPrivateKeySigner` in `NostrClient` to fix TypeError in signer tests.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/nostr/client.js

@@ -214,7 +214,8 @@ import { queueSignEvent } from "./signRequestQueue.js";
 import { EventsMap } from "./eventsMap.js";
 import { PersistenceManager } from "./managers/PersistenceManager.js";
 import { ConnectionManager } from "./managers/ConnectionManager.js";
-import { SignerManager } from "./managers/SignerManager.js";
+import { SignerManager, resolveSignerCapabilities } from "./managers/SignerManager.js";
+import { RelayBatchFetcher } from "./relayBatchFetcher.js";
 
 function normalizeProfileFromEvent(event) {
   if (!event || !event.content) return null;
@@ -580,6 +581,7 @@ export class NostrClient {
   constructor() {
     this.connectionManager = new ConnectionManager(this);
     this.signerManager = new SignerManager(this);
+    this.relayBatchFetcher = new RelayBatchFetcher(this);
 
     /**
      * @type {Map<string, object>}
@@ -2907,6 +2909,13 @@ export class NostrClient {
    * @returns {Promise<import("nostr-tools").Event>} The signed and published edit event.
    * @throws {Error} If permission denied, ownership mismatch, or publish failure.
    */
+  registerPrivateKeySigner({ privateKey, pubkey }) {
+    const adapter = createNsecAdapter(privateKey, pubkey);
+    this.signerManager.setActiveSigner(adapter);
+    // Also set session actor for worker-based encryption
+    this.sessionActor = { privateKey, pubkey, source: "nsec" };
+  }
+
   async ensureActiveSignerForPubkey(pubkey) {
     return this.signerManager.ensureActiveSignerForPubkey(pubkey);
   }

js/nostr/managers/SignerManager.js

@@ -53,7 +53,7 @@ import { queueSignEvent } from "../signRequestQueue.js";
 import { signEventWithPrivateKey } from "../publishHelpers.js";
 import { ensureNostrTools, getCachedNostrTools } from "../toolkit.js";
 
-function resolveSignerCapabilities(signer) {
+export function resolveSignerCapabilities(signer) {
   const fallback = {
     sign: false,
     nip44: false,