Function cancelPendingRequestForAction

Targeted cancel for a single combat tracker action's in-flight prompt — the GM "Mark Resolved" escape hatch's cancellation mechanism (module:documents/combat.mjs#markActionResolved). Unlike cancelAllPendingRequests (a blanket cancel of every outstanding request, intentionally no longer called from the advance-lock conflict path — see .claude/contexts/combat.md's "Advance-During-Pending-Prompt Race"), this only ever touches the request(s) tied to actionId, leaving every other in-flight prompt (for other actions, or non-action prompts) completely untouched.

Checks two registries in order, since which one holds the live entry depends on who's rendering the prompt:

1. _pendingRequests — this client (necessarily the lead GM, since combat resolution only ever runs there) dispatched the prompt to a delegate/ lead-GM on another client (e.g. the player who owns the target actor). Cancelling here rejects with BmsPromptAbort and also emits prompt.cancel so the remote client's rendered dialog closes too.
2. _activeRemotePrompts — this client is itself rendering the prompt locally because no other delegate was available (e.g. the GM's own interactive target/template/burst picker, or the Survey Environment dialog). Aborted via abortLocalPrompt, which invokes the renderer's registered abort function — every renderer's abort path ends in the same BmsPromptAbort throw as a normal user cancel.

Neither registry entry resolves/rejects synchronously in a way the caller can await directly (the reject only starts the unwind — the awaiting _resolveOneAction/system.resolve() chain still needs its own microtask turns, and for the local-render path a DOM click-simulation + finally cleanup, to actually finish propagating). Callers that need the associated ResolvePass claim to be released before proceeding (as markActionResolved does) must poll/await that separately once this returns found: true.