Backlog: Zoom API attendance integration

TL;DR

Today admin manually marks completion based on Aksara's external attendance system. Integrate Zoom API to pull attendance and auto-suggest completion.

Description

• Zoom Server-to-Server OAuth app.
• Pull participant join/leave times after each meeting.
• Match by email / phone to enrolled users.
• Compute attendance percentage; auto-mark completion above threshold (admin can override).
• Listed in PRD post-MVP roadmap.

Acceptance Criteria

• [ ] Zoom credentials in env; documented.
• [ ] Per-batch attendance report visible in admin.
• [ ] Auto-suggested completion for users above threshold.
• [ ] Manual override preserved.

Priority

• Priority: p3
• Rationale: nice-to-have; current manual flow works.

Dependencies

• None.

Links

• feat — PRD summary
• feat — certificates