refactor(model-fallback): fully encapsulate session state in factory closure

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

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

src/create-tools.ts

@@ -22,7 +22,7 @@ type CreateToolsResult = {
 export async function createTools(args: {
   ctx: PluginContext
   pluginConfig: OhMyOpenCodeConfig
-  managers: Pick<Managers, "backgroundManager" | "tmuxSessionManager" | "skillMcpManager">
+  managers: Pick<Managers, "backgroundManager" | "tmuxSessionManager" | "skillMcpManager" | "modelFallbackControllerAccessor">
 }): Promise<CreateToolsResult> {
   const { ctx, pluginConfig, managers } = args