feat(proxy-fitness): pool fitness registry + Smart rotation + pool-scoped retry

Pool/IP fitness registry (globalThis-backed, provider::model scopes, 5-min
cooldown, provider::* wildcard) fed by pool-scoped failures: freebuff
limited-IP / model-locked gates and opencode free per-IP limits. chatCore
retries a failed pool via another pool without locking the account; new
Smart rotation strategy (per-connection + no-auth providers) skips unfit
pools. Proxy Fitness dashboard page: active-block table with provider/IP
filters, per-record Clear and provider-scoped Clear All; egress column via
pool geo enrichment. Unit tests for the registry.

src/app/api/proxy-pools/route.js

@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { createProxyPool, getProviderConnections, getProxyPools } from "@/models";
+import { getPoolGeo } from "open-sse/services/poolGeo.js";
 
 function toBoolean(value) {
   if (value === "true") return true;
@@ -65,6 +66,8 @@ export async function GET(request) {
     const enrichedProxyPools = proxyPools.map((pool) => ({
       ...pool,
       boundConnectionCount: usageMap.get(pool.id) || 0,
+      // Egress geo from the background probe cache (null until first probe).
+      egress: getPoolGeo(pool.id) || null,
     }));
 
     return NextResponse.json({ proxyPools: enrichedProxyPools });