refactor(open-sse): P3§7 model defaults schema — centralize type/quotaFamily/strip/targetFormat

- Add providers/models/schema.js (MODEL_DEFAULTS + field resolvers)
- Accessors getModelTargetFormat/QuotaFamily/Strip use shared default resolvers
- getModelType keeps null contract unchanged; behavior verified equal
- No catalog forced into registry (models stay self-contained per docs decision)

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/providers/models/schema.js

@@ -1,32 +1,21 @@
-// Model schema (Mongoose-lite): central defaults + normalizer + 3-tier resolver (skeleton, not wired)
-
-// Centralized model defaults (caps declares positive capabilities)
+// Model defaults centralized (was scattered as `m.type || "llm"`, `quotaFamily || "normal"`, etc.)
 export const MODEL_DEFAULTS = {
   type: "llm",
   quotaFamily: "normal",
   strip: [],
-  targetFormat: null,
-  caps: { vision: false, audioIn: false, thinking: false }
+  targetFormat: null
 };
 
-// Normalize a raw model entry over defaults (deep-merge caps)
-export function normalizeModel(raw) {
-  return {
-    ...MODEL_DEFAULTS,
-    ...raw,
-    caps: { ...MODEL_DEFAULTS.caps, ...raw.caps },
-    upstreamModelId: raw.upstreamModelId || raw.id
-  };
+// Resolve a single field with its default (keeps accessor call-sites one-liners)
+export function modelType(model) {
+  return model?.type || MODEL_DEFAULTS.type;
 }
-
-// 3-tier fallback: defaults -> catalog canonical -> provider inline override (wins)
-export function resolveModel(catalog, ref) {
-  const raw = typeof ref === "string" ? { id: ref } : ref;
-  return {
-    ...MODEL_DEFAULTS,
-    ...catalog[raw.id],
-    ...raw,
-    caps: { ...MODEL_DEFAULTS.caps, ...catalog[raw.id]?.caps, ...raw.caps },
-    upstreamModelId: raw.upstreamModelId || catalog[raw.id]?.upstreamModelId || raw.id
-  };
+export function modelQuotaFamily(model) {
+  return model?.quotaFamily || MODEL_DEFAULTS.quotaFamily;
+}
+export function modelStrip(model) {
+  return model?.strip || [];
+}
+export function modelTargetFormat(model) {
+  return model?.targetFormat || MODEL_DEFAULTS.targetFormat;
 }