Refactor NIP-46 login UI to be cleaner and QR-first

- Simplified `components/login-modal.html` to center the QR code and use a "Copy Link" button instead of a large textarea.
- Updated `js/ui/loginModalController.js` to support the new DOM structure and error handling.
- Added `docs/nip46-roadmap.md` to document current state and future features.
- Fixed `NostrClient.destroy()` usage (synchronous void method) in `js/nostr/client.js`.
- Relaxed NIP-46 `connect` response validation in `js/nostr/client.js` and `js/nostr/nip46Client.js` to accept "ack" (case-insensitive) as a valid success signal, preventing timeouts with signers that do not echo the secret.

js/nostr/client.js

@@ -1787,7 +1787,8 @@ export class NostrClient {
             }
 
             if (secret) {
-              if (!resultValue || resultValue !== secret) {
+              const normalizedResult = resultValue ? resultValue.toLowerCase() : "";
+              if (resultValue !== secret && normalizedResult !== "ack") {
                 return;
               }
             }
@@ -2202,7 +2203,7 @@ export class NostrClient {
         message: error?.message || String(error),
         code: error?.code || null,
       });
-      await client.destroy().catch(() => {});
+      client.destroy();
       this.nip46Client = null;
       if (!remember) {
         clearStoredNip46Session();

js/nostr/nip46Client.js

@@ -1823,7 +1823,10 @@ export class Nip46RpcClient {
 
     if (this.secret) {
       const normalizedResult = typeof result === "string" ? result.trim() : "";
-      if (!normalizedResult || normalizedResult !== this.secret) {
+      if (
+        !normalizedResult ||
+        (normalizedResult !== this.secret && normalizedResult.toLowerCase() !== "ack")
+      ) {
         const error = new Error("Remote signer secret mismatch. Rejecting connection.");
         error.code = "nip46-secret-mismatch";
         throw error;