Refactor handle registry updates and improve key decoding

Removed 'healing' logic and authoritative update propagation from handle registry and gossip code, simplifying handle upserts to only update on strictly newer timestamps. Enhanced sodium-chat key handling with robust base64 decoding and key repair logic. Added scripts for key inspection and crypto testing. Deleted unused healing module.

src/lib/swarm/gossip.ts

@@ -91,8 +91,7 @@ export async function processGossip(
   // Process incoming handles
   let handlesResult = { added: 0, updated: 0 };
   if (payload.handles && payload.handles.length > 0) {
-    // PASS SENDER: This allows us to trust "authoritative" updates from the node itself
-    handlesResult = await upsertHandleEntries(payload.handles, payload.sender);
+    handlesResult = await upsertHandleEntries(payload.handles);
   }
 
   // Build our response with nodes/handles to share back
@@ -164,8 +163,7 @@ export async function gossipToNode(
 
     let handlesResult = { added: 0, updated: 0 };
     if (gossipResponse.handles && gossipResponse.handles.length > 0) {
-      // PASS TARGET: If we gossiped TO them, and they replied, treat their reply as authoritative
-      handlesResult = await upsertHandleEntries(gossipResponse.handles, targetDomain);
+      handlesResult = await upsertHandleEntries(gossipResponse.handles);
     }
 
     await markNodeSuccess(targetDomain);