appcues: AI-optimize MCP action set

Appcues has no actions built in Pipedream today — there's nothing an agent can do with this integration yet. We'd like to build an initial action set so an agent can manage user onboarding flows and engagement data, and so each tool is easy for an agent to configure.

A few things an agent can't do today, for example:
- Look up users and their profile/event data
- Create or update a user segment
- List active flows (tours, checklists, banners) and their status
- Pull completion/engagement analytics for a flow or segment

**API reference:** https://api.appcues.com/v2/docs

**Add marker:**
When a component is AI-optimized, add this as the first line of the file:
```
// x-pd-ai: optimized
```
Add it to each action file and to the app's `.mjs` file.

Start with the Appcues API reference and inspect the integration's action files and app's .mjs file. Implement an initial action set for user data, segments, flows, and engagement analytics, and confirm each action file and the .mjs file begins with the required AI-optimization marker.

Written by the indexing model from the issue text.