feat(platform): add membership management system with profiles and admin dashboard

No files, tests, or entry points are named. Start with sub-issue #1917 and follow #1918 through #1921 in the stated order, reviewing the existing React and TypeScript app first; the work is done when authentication, profiles, the admin dashboard, and site integration meet the listed requirements.

Summary

Build a membership management system where community members can create accounts, sign in, and manage rich profiles, and where leadership has an admin dashboard for analytics, member management, and trend visualization.

Sub-Issues (Implementation Order)

1. #1917 — Database schema & infrastructure (NeonDB + Drizzle ORM)
2. #1918 — Authentication (WorkOS integration, RBAC)
3. #1919 — Member profiles (public pages, edit flow, directory)
4. #1920 — Admin dashboard (analytics, member management, audit log)
5. #1921 — Site integration (nav updates, auth UI, profile linking)

Tech Stack

• Auth: WorkOS (User Management API, SSO/SAML for institutions)
• Database: NeonDB serverless Postgres
• ORM: Drizzle ORM with Drizzle Kit migrations
• Frontend: React 19 + TypeScript 6 + Tailwind CSS 4 (existing app)
• Charts: Recharts or @visx for admin analytics
• Storage: S3-compatible (profile photo uploads)

Requirements

Authentication & Accounts

• WorkOS integration (SSO, email/password, social login)
• Member registration with email verification
• Role-based access: member, admin (board/staff)
• Session management and secure sign-out

Member Profiles (GH + LinkedIn style)

• Profile photo, name, pronouns, bio
• Institution and role/title
• Links: GitHub, LinkedIn, ORCID, personal website
• Research interests / tags
• Working group and affinity group memberships
• Public profile page + edit interface

Admin Dashboard

• Member directory with search, filter, sort
• Growth analytics with data visualizations
• Add/remove members, edit roles
• Export member data (CSV)
• Audit log of admin actions