refactor(app): DRY pass — split large files, extract shared utils

S1: delete page.new.js (1724L abandoned) + remove dead getAntigravityProjectId
S2: split large files by natural seams
  - usage.js → usage/{github,google,claude,codex,kiro,minimax,misc,shared}.js
  - media-providers page → components/{Embedding,Tts,Generic,Stt}ExampleCard.js
  - EndpointPageClient → endpointConstants.js + endpointPing.js + components/
  - tokenRefresh.js → tokenRefresh/{dedup,providers}.js
  - ProviderLimits/index.js: 16 pure fn + 9 constants → utils.js
  - oauth/providers.js: 7 pure helpers → providerHelpers.js
S3: shared utils
  - getModelKind(m, fallback) → shared/constants/models.js (replaces 20× m.kind||m.type)
  - getStatusVariant → shared/utils/connectionStatus.js (dedup ConnectionRow/ConnectionsCard)
  - sseChunk → open-sse/utils/sse.js (dedup grok-web/perplexity-web)
  - fetchWithTimeout → usage/shared.js (replace 4× AbortController pattern in google.js)
fix: enableObservability2 field name in requestDetailsRepo
Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/services/usage/shared.js

@@ -0,0 +1,70 @@
+/**
+ * Shared usage helpers (cross-provider)
+ */
+
+import { PROVIDERS } from "../../providers/index.js";
+import { proxyAwareFetch } from "../../utils/proxyFetch.js";
+
+// usage endpoints: single source from registry transport.usage
+export const U = (id) => PROVIDERS[id]?.usage || {};
+
+/**
+ * Parse reset date/time to ISO string
+ * Handles multiple formats: Unix timestamp (ms), ISO date string, etc.
+ */
+export function parseResetTime(resetValue) {
+  if (!resetValue) return null;
+
+  try {
+    // If it's already a Date object
+    if (resetValue instanceof Date) {
+      return resetValue.toISOString();
+    }
+
+    // Unix timestamps from provider APIs may be seconds or milliseconds.
+    if (typeof resetValue === 'number') {
+      return new Date(resetValue < 1e12 ? resetValue * 1000 : resetValue).toISOString();
+    }
+
+    // If it's a numeric string, treat it like a Unix timestamp too.
+    if (typeof resetValue === 'string') {
+      if (/^\d+$/.test(resetValue)) {
+        const timestamp = Number(resetValue);
+        return new Date(timestamp < 1e12 ? timestamp * 1000 : timestamp).toISOString();
+      }
+      return new Date(resetValue).toISOString();
+    }
+
+    return null;
+  } catch (error) {
+    console.warn(`Failed to parse reset time: ${resetValue}`, error);
+    return null;
+  }
+}
+
+export function toFiniteNumber(value, fallback = 0) {
+  if (typeof value === "number" && Number.isFinite(value)) return value;
+  if (typeof value === "string" && value.trim()) {
+    const parsed = Number(value);
+    if (Number.isFinite(parsed)) return parsed;
+  }
+  return fallback;
+}
+
+export function normalizeCloudCodeProjectId(project) {
+  if (typeof project === "string") return project.trim() || null;
+  if (project && typeof project === "object" && typeof project.id === "string") {
+    return project.id.trim() || null;
+  }
+  return null;
+}
+
+export async function fetchWithTimeout(url, opts, ms = 10000, proxyOptions = null) {
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => controller.abort(), ms);
+  try {
+    return await proxyAwareFetch(url, { ...opts, signal: controller.signal }, proxyOptions);
+  } finally {
+    clearTimeout(timeoutId);
+  }
+}