Standardize on top-level triggerer property (#361)

* Standardize on top-level `triggerer` property

- Rename `triggeringUser` → `triggerer` as the single top-level payload property
- Remove redundant `triggerer` from `FixReviewEvent`, add `approvedOnly` boolean
- Auto-apply `approved_by` filtering in `get_review_comments` when `approvedOnly` is set
- Auto-assign created PRs to the triggerer
- Simplify `AddressReviews` mode prompt
- Accept both `triggerer` and `triggeringUser` in schema for backward compat

* Address review feedback: simplify approved_only, remove addAssignees, drop approved_by param

* Fix formatting in `action/mcp/pr.ts`

* re-add triggeringUser backward-compat fallback in payload schema

* auto-assign created PRs to the triggerer

* Revert "auto-assign created PRs to the triggerer"

This reverts commit c088c425fea33793eb299a001ffd253798d2c674.

* Revert "re-add triggeringUser backward-compat fallback in payload schema"

This reverts commit ae5b3cb3f1377cd4a634b2d48962c785c31013f3.

* backend compat

* tweak prompt to ensure compat

* Address review feedback

* chore: remove triggeringUser fallback

---------

Co-authored-by: pullfrog[bot] <226033991+pullfrog[bot]@users.noreply.github.com>
Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>
Co-authored-by: Colin McDonnell <colinmcd94@gmail.com>

utils/payload.ts

@@ -19,7 +19,8 @@ export const JsonPayload = type({
   version: "string",
   "agent?": AgentName.or("undefined"),
   prompt: "string",
-  "triggeringUser?": "string | undefined",
+  "triggerer?": "string | undefined",
+
   "eventInstructions?": "string",
   "repoInstructions?": "string",
   "event?": "object",
@@ -167,8 +168,8 @@ export function resolvePayload(
     version: jsonPayload?.version ?? packageJson.version,
     agent: resolvedAgent,
     prompt,
-    triggeringUser:
-      jsonPayload?.triggeringUser ??
+    triggerer:
+      jsonPayload?.triggerer ??
       // it's not a common use case but GITHUB_ACTOR can be a user when the workflow is manually triggered by a user through GitHub Actions UI
       (!isPullfrog(process.env.GITHUB_ACTOR) ? process.env.GITHUB_ACTOR : undefined),
     eventInstructions: jsonPayload?.eventInstructions,