refactor(model-core): remove src back-imports via core utilities and adapter

- move fuzzyMatchModel and transformModelForProvider into model-core

- replace connected-providers re-export with adapter contract

- route shared wrappers through model-core exports

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

packages/model-core/src/index.ts

@@ -24,6 +24,11 @@ export * from "./model-format-normalizer"
 export * from "./model-normalization"
 export * from "./model-string-parser"
 export * from "./model-sanitizer"
+export {
+	fuzzyMatchModel,
+	isModelAvailable,
+} from "./model-availability"
+export { transformModelForProvider } from "./provider-model-id-transform"
 export * from "./fallback-chain-from-models"
 export * from "./known-variants"
 export {