feat: Add Pipedream connector skill (HTTP proxy)

[major-connector-creator]

Summary

Adds a SKILL.md file for the Pipedream connector under plugins/shared/skills/resources_pipedream/.

Since Pipedream is a proxy-only connector, the skill focuses on the generic HTTP proxy MCP tools (mcp__resources__http_proxy_get and mcp__resources__http_proxy_invoke) rather than subtype-specific tools.

What's included

• resources_pipedream/SKILL.md: Describes how to use the Pipedream connector via HTTP proxy tools, including:
  • Example calls for listing apps, getting current user, working with Connect API
  • Tips about OAuth2 Client Credentials auth (handled automatically by the connector)
  • API path conventions (/v1/...)
  • Links to Pipedream REST API and Connect API docs

Related PRs

• Monorepo: Adds Go backend handler, API schemas, frontend panel
• Package: No typed client needed (proxy-only)