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>

src/shared/model-resolver.ts

@@ -1,12 +1,28 @@
+import {
+	resolveModel,
+	resolveModelWithFallback as resolveModelWithFallbackFromCore,
+	normalizeFallbackModels,
+	flattenToFallbackModelStrings,
+} from "@oh-my-opencode/model-core"
+import type {
+	ModelResolutionInput,
+	ExtendedModelResolutionInput,
+} from "@oh-my-opencode/model-core"
+import * as connectedProvidersCache from "./connected-providers-cache"
+
+export { resolveModel, normalizeFallbackModels, flattenToFallbackModelStrings }
+
+type CoreModelResolutionResult = ReturnType<typeof resolveModelWithFallbackFromCore>
+export type ModelResolutionResult = Exclude<CoreModelResolutionResult, undefined>
+export type ModelSource = ModelResolutionResult["source"]
+
+export function resolveModelWithFallback(
+	input: ExtendedModelResolutionInput,
+): CoreModelResolutionResult {
+	return resolveModelWithFallbackFromCore(input, connectedProvidersCache)
+}
+
 export type {
-  ModelResolutionInput,
-  ModelSource,
-  ModelResolutionResult,
-  ExtendedModelResolutionInput,
-} from "@oh-my-opencode/model-core"
-export {
-  resolveModel,
-  resolveModelWithFallback,
-  normalizeFallbackModels,
-  flattenToFallbackModelStrings,
-} from "@oh-my-opencode/model-core"
+	ModelResolutionInput,
+	ExtendedModelResolutionInput,
+}