feat(discovery): extend discovery span metadata for Phase 529

Add peerCount on discovery.list, listingTtlMs/refreshedAt on mesh,
beforeListed on publish, and channelCount on join span ends.

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

index.js

@@ -7962,7 +7962,9 @@ class PearcordPlatform extends EventEmitter {
         listed: !!listed,
         hasInvite: !!inviteCode,
         memberCount,
-        changed: beforeListed !== !!listed
+        changed: beforeListed !== !!listed,
+        beforeListed,
+        announced: !!listed
       })
       return { guildId, listed: !!listed }
     } catch (err) {
@@ -7987,7 +7989,9 @@ class PearcordPlatform extends EventEmitter {
         spanKind: 'discovery.join',
         guildId: guild?.id || null,
         joined: !!guild,
-        activeChannelId: this.activeChannelId || null
+        activeChannelId: this.activeChannelId || null,
+        inviteLen: String(inviteCode).length,
+        channelCount: guild?.channels?.length ?? 0
       })
       return guild
     } catch (err) {
@@ -12896,7 +12900,8 @@ class PearcordPlatform extends EventEmitter {
             filteredCount,
             queryLen: String(filter?.query || '').length,
             sort: filter?.sort || 'relevance',
-            minMembers: Number(filter?.minMembers || 0)
+            minMembers: Number(filter?.minMembers || 0),
+            peerCount: this.discovery?.peers?.size ?? 0
           })
         }
       } else {
@@ -12917,7 +12922,8 @@ class PearcordPlatform extends EventEmitter {
               filteredCount,
               queryLen: String(filter?.query || '').length,
               sort: filter?.sort || 'relevance',
-              minMembers: Number(filter?.minMembers || 0)
+              minMembers: Number(filter?.minMembers || 0),
+              peerCount: this.discovery?.peers?.size ?? 0
             })
           } else {
             publicListings = await this.discovery.listPublicListings()
@@ -12963,7 +12969,9 @@ class PearcordPlatform extends EventEmitter {
           peers: discoveryStats?.peers ?? 0,
           listings: discoveryStats?.listings ?? publicListings.length,
           meshLive: !!discoveryStats?.meshLive,
-          hadCachedStats
+          hadCachedStats,
+          listingTtlMs: discoveryStats?.listingTtlMs ?? null,
+          refreshedAt: this._discoveryMeshRefreshAt || null
         })
         this._cachedDiscoveryStats = discoveryStats
         this._cachedDiscoveryStatsAt = now