Fix thread parent event loading regression

This fixes a regression where ThreadModel would no longer look at
NostrDB saved notes for parent events, causing some instability on
thread loading — especially in poor networking conditions.

This was fixed by adding a call that searches for parent events in
EventCache/NostrDB each time an event is added to the ThreadModel.

That `add_event` function is the ideal spot to place the call because it
is the only interface used for all information updates incoming to the
ThreadModel, including:
- anytime an event is loaded from the network into the thread model.
- when the ThreadModel is first initialized, with an initial event.

Fixes: 74d5bee1f6
Changelog-Fixed: Fixed an issue where threads would not load properly
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damus/Models/ThreadModel.swift

@@ -136,6 +136,16 @@ class ThreadModel: ObservableObject {
 
         event_map.add(event: ev)
         
+        // Add all parent events that we have on EventCache (and subsequently on NostrDB)
+        // This helps ensure we include as many locally-stored notes as possible — even on poor networking conditions
+        damus_state.events.parent_events(event: ev, keypair: damus_state.keypair).forEach {
+            // Note: Nostr threads are cryptographically guaranteeed to be acyclic graphs, which means there is no risk of infinite recursion in this call
+            add_event(
+                $0,  // The `lookup` function in `parent_events` turns the event into an "owned" object, so we do not need to clone here
+                keypair: damus_state.keypair
+            )
+        }
+
         // Publish changes
         objectWillChange.send()
     }