Phase 957: gossip outbox stats build extract (v0.8.924)

Add guild-mesh-gossip-outbox-stats-build with lane alert thresholds,
outbox stats resolve, and replication diagnostics gossip slice. Gossip
view and partition-heal mixins delegate without behavior change.

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

mixins/runtime/guild-sync/platform-guild-sync-gossip-view-mixin.js

@@ -1,38 +1,18 @@
 'use strict'
 
 const { getListingTtlMs } = require('pearcord-discovery')
+const {
+  buildGossipLaneAlertThresholds,
+  buildGossipLaneAlertsFromCounts
+} = require('../../../guild-mesh-gossip-outbox-stats-build')
 
 const platformGuildSyncGossipViewMixin = {
   _gossipLaneAlertThresholds () {
-    return {
-      message: Math.max(
-        8,
-        Number(process.env.PEARCORD_GOSSIP_LANE_ALERT_MESSAGE) || 48
-      ),
-      presence: Math.max(
-        8,
-        Number(process.env.PEARCORD_GOSSIP_LANE_ALERT_PRESENCE) || 32
-      ),
-      audit: Math.max(8, Number(process.env.PEARCORD_GOSSIP_LANE_ALERT_AUDIT) || 24),
-      default: Math.max(8, Number(process.env.PEARCORD_GOSSIP_LANE_ALERT_DEFAULT) || 16)
-    }
+    return buildGossipLaneAlertThresholds()
   },
 
   _gossipLaneAlertsFromCounts (laneCounts = {}) {
-    const thresholds = this._gossipLaneAlertThresholds()
-    const alerts = []
-    for (const lane of ['message', 'presence', 'audit', 'default']) {
-      const count = Number(laneCounts[lane]) || 0
-      const threshold = thresholds[lane] || 16
-      if (count < threshold) continue
-      alerts.push({
-        lane,
-        count,
-        threshold,
-        severity: count >= threshold * 2 ? 'high' : 'warn'
-      })
-    }
-    return alerts
+    return buildGossipLaneAlertsFromCounts(laneCounts, this._gossipLaneAlertThresholds())
   },
 
   _sparseAckSyncRowsForView (guildId) {