fix(nostr): await nip-07 extension injection to resolve race conditions

This commit fixes a critical race condition where `window.nostr` might not be injected
before the app attempts to use it, causing failures in decryption (subscriptions, hashtags, DMs)
and login flows.

Changes:
- Updated `ensureExtensionPermissions` in `js/nostr/client.js` to verify `window.nostr` existence
  even when permissions are cached. If missing, it now awaits `waitForNip07Extension` instead of
  returning a false success.
- Updated `ensureActiveSignerForPubkey` in `js/nostr/client.js` to wait for the extension
  if permissions are cached but `window.nostr` is missing, ensuring a valid signer is created.

This ensures that the "Performance Analysis" optimization (skipping `enable()` calls based on cache)
does not break functionality when the extension injection is delayed.

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

js/nostr/client.js

@@ -2584,6 +2584,16 @@ export class NostrClient {
     );
 
     if (!outstanding.length) {
+      // Even if permissions are cached, we must ensure the extension object is actually
+      // injected and available on the window before returning success.
+      // This prevents race conditions where the app loads faster than the extension.
+      if (typeof window !== "undefined" && !window.nostr) {
+        try {
+          await waitForNip07Extension(3000);
+        } catch (error) {
+          return { ok: false, error: new Error("extension-unavailable") };
+        }
+      }
       return { ok: true };
     }
 
@@ -2618,8 +2628,20 @@ export class NostrClient {
       return existingSigner;
     }
 
-    const extension =
+    let extension =
       typeof window !== "undefined" && window && window.nostr ? window.nostr : null;
+
+    // If the extension is missing but we have cached permissions, it implies the user
+    // previously logged in with an extension. We should wait briefly for injection
+    // to resolve the common race condition where the app loads faster than the extension.
+    if (!extension && this.extensionPermissionCache && this.extensionPermissionCache.size > 0) {
+      try {
+        extension = await waitForNip07Extension(3000);
+      } catch (error) {
+        // Fall through to existing signer check
+      }
+    }
+
     if (!extension) {
       return existingSigner;
     }