fix(prompt-async-gate): retry object-form path on runtime type error (#4417)

Atlas task() with run_in_background=false crashed with 'The "path" property must be of type string, got object' from Node's path.isAbsolute validation upstream of the SDK.

All callers (sync-prompt-sender, boulder-continuation-injector, idle-event, session-route, model-suggestion-retry) already route through dispatchInternalPrompt, so centralizing the compatibility shim in prompt-async-gate.ts covers every Bug 1 site without touching individual hooks.

On TypeError matching the object-path signature, retry once with path collapsed to its id string. Types broaden PromptSessionPath to string | { id }.

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

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

src/shared/prompt-async-gate/types.ts

@@ -1,5 +1,7 @@
+export type PromptSessionPath = { readonly id?: string } | string
+
 export type PromptAsyncInput = {
-  readonly path?: { readonly id?: string }
+  readonly path?: PromptSessionPath
   readonly body?: unknown
   readonly query?: unknown
   readonly signal?: unknown