feat(models): refresh model capabilities from models.dev in the background

Capability tables are hand-maintained, so a model gains vision or a wider
context only when someone notices and edits the file. This adds a daily
sync that fills the gap for models already in the registry.

How it decides:

- Modalities (vision/pdf/audio/video) belong to the MODEL — every gateway
  serving glm-5.3-flash serves the same weights — so they are keyed by
  model id and shared. A majority of sources must declare one, which keeps
  out lone mis-declarations: minimax-m2.5 (1 of 45), glm-4.7 (1 of 44) and
  gpt-oss-120b (2 of 76) are text-only despite a reseller claiming vision.
- Context/output limits belong to the GATEWAY — each truncates differently
  (glm-5 ships as 202752/16384 on one host and 204800/131072 on another) —
  so they are keyed by provider + model and only the matching provider's
  own numbers are trusted.

Both layers are strictly additive and sit BELOW the hand-written tables,
which short-circuit first. A capability already true stays true.

Mechanics: worker thread (the 4MB parse would block the loop ~20ms),
ETag so an unchanged catalog costs one empty request, 60s startup delay,
30min backoff on failure, MODEL_CATALOG_SYNC=off to disable. Only the
~57KB delta is kept; lookups cost ~0.1us via an mtime-guarded cache.

capabilities.js is bundled into the browser through useModelCaps, so it
cannot import node:fs — the server injects the reader via
setCatalogSource() from instrumentation.

visionPatterns.js is the last resort: a model nobody has catalogued yet
still accepts images when its id says so (qwen3-vl-plus, glm-4.6v, llava),
with image-generation and embedding ids excluded.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/app/api/models/catalog-sync/route.js

@@ -0,0 +1,31 @@
+import { NextResponse } from "next/server";
+import fs from "node:fs";
+import { getSyncState, syncModelCatalog } from "@/lib/modelCatalog/sync.js";
+import { CATALOG_FILE } from "open-sse/providers/catalogOverride.js";
+
+// GET /api/models/catalog-sync - Sync status and what the catalog currently holds
+export async function GET() {
+  const state = getSyncState();
+  let catalog = null;
+  try {
+    const parsed = JSON.parse(fs.readFileSync(CATALOG_FILE, "utf8"));
+    catalog = {
+      syncedAt: parsed.syncedAt,
+      models: Object.keys(parsed.models || {}).length,
+      providers: Object.keys(parsed.providers || {}).length,
+      bytes: fs.statSync(CATALOG_FILE).size,
+    };
+  } catch {
+    catalog = null;
+  }
+  return NextResponse.json({ ...state, catalog });
+}
+
+// POST /api/models/catalog-sync - Run a sync now instead of waiting for the timer
+export async function POST() {
+  const result = await syncModelCatalog();
+  if (!result) {
+    return NextResponse.json({ error: getSyncState().lastError || "sync in progress" }, { status: 503 });
+  }
+  return NextResponse.json({ success: true, result });
+}