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>

src/app/(dashboard)/dashboard/providers/[id]/page.js

@@ -6,7 +6,7 @@ import Link from "next/link";
 import Image from "next/image";
 import { Card, Button, Badge, Input, Modal, CardSkeleton, OAuthModal, KiroOAuthWrapper, CursorAuthModal, IFlowCookieModal, GitLabAuthModal, Toggle, Select, EditConnectionModal, NoAuthProxyCard, ConfirmModal } from "@/shared/components";
 import { OAUTH_PROVIDERS, APIKEY_PROVIDERS, FREE_PROVIDERS, FREE_TIER_PROVIDERS, WEB_COOKIE_PROVIDERS, getProviderAlias, isOpenAICompatibleProvider, isAnthropicCompatibleProvider, AI_PROVIDERS, THINKING_CONFIG } from "@/shared/constants/providers";
-import { getModelsByProviderId } from "@/shared/constants/models";
+import { getModelsByProviderId, getModelKind } from "@/shared/constants/models";
 import { useCopyToClipboard } from "@/shared/hooks/useCopyToClipboard";
 import { translate } from "@/i18n/runtime";
 import { fetchSuggestedModels } from "@/shared/utils/providerModelsFetcher";
@@ -914,7 +914,7 @@ export default function ProviderDetailPage() {
     const allModels = [
       ...models,
       ...kiloFreeModels.filter((fm) => !models.some((m) => m.id === fm.id)),
-    ].filter((m) => { const k = m.kind || m.type; return !k || k === "llm"; });
+    ].filter((m) => { const k = getModelKind(m); return !k || k === "llm"; });
     const disabledSet = new Set(disabledModelIds);
     const displayModels = allModels.filter((m) => !disabledSet.has(m.id));
     const disabledDisplayModels = allModels.filter((m) => disabledSet.has(m.id));
@@ -1449,7 +1449,7 @@ export default function ProviderDetailPage() {
             const allIds = [
               ...models,
               ...kiloFreeModels.filter((fm) => !models.some((m) => m.id === fm.id)),
-            ].filter((m) => { const k = m.kind || m.type; return !k || k === "llm"; }).map((m) => m.id);
+            ].filter((m) => { const k = getModelKind(m); return !k || k === "llm"; }).map((m) => m.id);
             const activeIds = allIds.filter((id) => !disabledModelIds.includes(id));
             return (
               <div className="flex gap-2">