Metrics: Track post-signup actions (subtask of #297)

[superdav42]

Subtask of #297 (Finish Metrics and Onboarding).

Scope: Track actions taken by users after signup — creating posts, custom post types, registering additional users, WooCommerce sales within subsites.

Acceptance criteria:

• Post-signup actions tracked: post creation, CPT creation, user registration, WooCommerce orders
• Events linked to the originating membership/subsite
• Admin can view per-subsite activity metrics

Parent: #297
Blocked-by: #398 (signup flow metrics must be in place first)

[superdav42]

Resolved by PR #416.

What was implemented:

• New Post_Signup_Activity_Manager tracks four post-signup actions on customer subsites:

  • Post creation (subsite_post_created)
  • Custom post type entry creation (subsite_cpt_created)
  • User added to subsite (subsite_user_registered)
  • WooCommerce order placed (subsite_woocommerce_order)

• Events are linked to the originating site/membership (object_type='site', object_id=<blog_id>)

• Admin can view per-subsite activity metrics in the existing Events widget on the site edit page (Network Admin → Sites → [site] → Events tab) — no new UI required

• All four event types are also available in the webhook event picker

[superdav42]

Implemented and merged in PR #416.

What was delivered:

• Post_Signup_Activity_Manager tracks four post-signup actions on customer subsites:
  • Post creation (subsite_post_created)
  • Custom post type entry creation (subsite_cpt_created)
  • User added to subsite (subsite_user_registered)
  • WooCommerce order created (subsite_woocommerce_order)
• Events are linked to the originating site (object_type='site', object_id=blog_id) and carry membership payload
• Admin can view per-subsite activity in the existing Events widget on the site edit page — no new UI required
• Main site and non-WU-managed blogs are skipped automatically