Refactor fetchListIncrementally to use RelayBatchFetcher

Extracted the complex incremental fetching logic from NostrClient into a dedicated RelayBatchFetcher class to improve maintainability and readability.

Also includes necessary fixes for SignerManager and Client regressions exposed by the refactor:
- Restored missing `registerPrivateKeySigner` and `installNip46Client` methods.
- Fixed `SignerManager.ensureSessionActor` to correctly generate session keys when missing.
- Fixed `SignerManager.ensureExtensionPermissions` logic.
- Exposed `signEventWithPrivateKey` on SignerManager for consistency.
- Fixed `isSessionActor` logic to correctly identify logged-in users vs session actors.

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

js/nostr/client.js

@@ -2932,6 +2932,10 @@ export class NostrClient {
     return this.signerManager.connectRemoteSigner(params);
   }
 
+  installNip46Client(client) {
+    this.signerManager.installNip46Client(client);
+  }
+
   async useStoredRemoteSigner(options) {
     return this.signerManager.useStoredRemoteSigner(options);
   }

js/nostr/managers/SignerManager.js

@@ -47,6 +47,7 @@ import {
   summarizeUrlForLog,
 } from "../nip46LoggingUtils.js";
 
+import { bytesToHex } from "../../../vendor/crypto-helpers.bundle.min.js";
 import { devLogger, userLogger } from "../../utils/logger.js";
 import { createPrivateKeyCipherClosures } from "../signerHelpers.js";
 import { queueSignEvent } from "../signRequestQueue.js";
@@ -315,21 +316,45 @@ export class SignerManager {
 
   async ensureSessionActor() {
     if (this.sessionActor) {
-      return this.sessionActor;
+      return this.sessionActor.pubkey;
     }
 
     if (this.lockedSessionActor) {
-      return this.lockedSessionActor;
+      return this.lockedSessionActor.pubkey;
     }
 
     const storedEntry = readStoredSessionActorEntry();
     if (storedEntry) {
       this.lockedSessionActor = storedEntry;
       this.sessionActor = storedEntry;
-      return storedEntry;
+      return storedEntry.pubkey;
     }
 
-    return null;
+    const tools = await ensureNostrTools();
+    let privateKey = "";
+    if (tools && typeof tools.generateSecretKey === "function") {
+      const secret = tools.generateSecretKey();
+      privateKey = bytesToHex(secret);
+    } else if (tools && typeof tools.generatePrivateKey === "function") {
+      privateKey = tools.generatePrivateKey();
+    } else {
+      throw new Error("Failed to generate session actor: nostr-tools missing key generation.");
+    }
+
+    let pubkey = "";
+    if (tools && typeof tools.getPublicKey === "function") {
+      pubkey = tools.getPublicKey(privateKey);
+    }
+
+    const newActor = {
+      pubkey,
+      privateKey,
+      source: "generated",
+      createdAt: Date.now(),
+    };
+
+    this.sessionActor = newActor;
+    return pubkey;
   }
 
   clearStoredSessionActor() {
@@ -557,6 +582,16 @@ export class SignerManager {
     return { pubkey: normalized, signer: adapter };
   }
 
+  installNip46Client(client) {
+    if (!client) {
+      return;
+    }
+    this.nip46Client = client;
+    this.pubkey = client.userPubkey || client.remotePubkey; // Fallback
+    this.setActiveSigner(client.getActiveSigner());
+    this.emitRemoteSignerChange();
+  }
+
   async connectRemoteSigner({
     connectionString,
     remember = true,
@@ -903,6 +938,10 @@ export class SignerManager {
     };
   }
 
+  signEventWithPrivateKey(event, privateKey) {
+    return signEventWithPrivateKey(event, privateKey);
+  }
+
   logout() {
     const previousPubkey = this.pubkey;
     this.pubkey = null;

js/nostr/sessionActor.js

@@ -484,7 +484,17 @@ export function clearStoredSessionActor() {
 
 export function isSessionActor(nostrClient) {
   const sa = nostrClient?.sessionActor;
-  return !!sa && sa.source !== "nsec";
+  if (!sa) {
+    return false;
+  }
+  if (
+    nostrClient?.pubkey &&
+    sa.pubkey &&
+    nostrClient.pubkey !== sa.pubkey
+  ) {
+    return false;
+  }
+  return sa.source !== "nsec";
 }
 
 function _closeSessionActorDb() {