feat(dm): implement incremental delivery for direct messages

- Added `onMessage` callback to `NostrClient.listDirectMessages` to stream decrypted messages.
- Updated `NostrService.loadDirectMessages` to use the callback and trigger `applyDirectMessage` incrementally.
- Updated `ProfileModalController` to allow rendering updates during the initial load if the reason is `load-incremental`.
- Verified changes with existing tests and code review.

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

js/nostr/client.js

@@ -4480,6 +4480,13 @@ export class NostrClient {
         });
         if (decrypted?.ok) {
           messages.push(decrypted);
+          if (typeof options.onMessage === "function") {
+            try {
+              options.onMessage(decrypted);
+            } catch (error) {
+              devLogger.warn("[nostr] onMessage callback threw:", error);
+            }
+          }
         }
       } catch (error) {
         devLogger.warn("[nostr] Failed to decrypt DM event during list.", {

js/services/nostrService.js

@@ -958,6 +958,9 @@ export class NostrService {
         ...options,
         limit: resolvedLimit,
         decryptLimit: resolvedDecryptLimit,
+        onMessage: (message) => {
+          this.applyDirectMessage(message, { reason: "load-incremental" });
+        },
       });
     } catch (error) {
       userLogger.warn("[nostrService] Failed to load direct messages", error);

js/ui/profileModalController.js

@@ -4970,7 +4970,10 @@ export class ProfileModalController {
   }
 
   handleDirectMessagesUpdated(detail = {}) {
-    if (this.activeMessagesRequest) {
+    if (
+      this.activeMessagesRequest &&
+      detail?.reason !== "load-incremental"
+    ) {
       return;
     }