fix(models): stabilize proxy endpoint refresh behavior

* fix: support large proxy model endpoint refresh

Large OpenAI-compatible proxy endpoints can expose hundreds of models and make /v1/models slow. Treating those endpoints like local model servers caused model picker opens and background probes to repeatedly hit /models, producing timeouts and making otherwise usable endpoints appear offline.

Make model endpoint discovery cached-first for normal UI usage, add explicit proxy/API classification and refresh policy fields, exclude proxy/API endpoints from aggressive local probing, and preserve cached models when refresh fails.

Manual Test/Add/Refresh actions still fetch the full model list with longer timeouts so users can intentionally import large proxy model lists without blocking normal model picker usage.

* fix: preserve endpoint ping status semantics

static/js/models.js

@@ -16,6 +16,7 @@ import { sortModelIds } from './modelSort.js';
 let API_BASE = '';
 let _cachedItems = []; // cached /api/models items for model-switch dropdown
 let _lastFetchTime = 0;
+let _fetchInflight = null;
 const _FETCH_CACHE_TTL = 30000; // 30s client-side cache for /api/models
 const COLLAPSE_KEY = 'odysseus-models-collapsed';
 const FAVORITES_KEY = 'odysseus-model-favorites';
@@ -176,8 +177,15 @@ export async function refreshModels(force = false) {
     box.appendChild(_loadingSpinner.createElement());
     _loadingSpinner.start();
     try {
-      const res = await fetch(`${API_BASE}/api/models`);
-      const data = await res.json();
+      if (!_fetchInflight) {
+        _fetchInflight = fetch(`${API_BASE}/api/models`, { credentials: 'same-origin' })
+          .then(async (res) => {
+            if (!res.ok) throw new Error(`HTTP ${res.status}`);
+            return res.json();
+          })
+          .finally(() => { _fetchInflight = null; });
+      }
+      const data = await _fetchInflight;
       _lastFetchTime = Date.now();
       _cachedItems = data.items || [];
     } catch (e) {