Add regional chapters and industry event presence features

[bokelley]

Summary

Enable user location tracking and event groups for member engagement:

• Add user location tracking (city, country) with migration 105
• Add event groups (committee_type: 'event') linked to industry events with migration 106
• Implement Slack channel auto-sync: joining a channel auto-adds users to working groups
• Add admin UI sections for event groups in Events admin page
• Add 'event' committee type filter to Working Groups admin page
• Create Addie tools for member-driven chapter creation
• Add UUID validation and member count to event group API endpoints
• Fix SQL injection in findChaptersNearLocation with proper LIKE escaping

This enables temporary "chapter-like" groups for industry events like CES and Cannes Lions, where Slack channel membership automatically syncs to working group membership.

Key Changes

New Migrations

• 105_user_location.sql - Adds city, country, location_source to users table; seeds location and chapter interest insight goals
• 106_event_groups.sql - Adds 'event' committee type, event linkage columns, interest tracking on memberships

Backend

• working-group-db.ts - Event group CRUD, chapter lookup, Slack channel lookup
• events.ts routes - Event group GET/POST endpoints with UUID validation
• slack/events.ts - Auto-add users to working groups when they join linked Slack channels
• slack/client.ts - createChannel() and setChannelPurpose() functions
• addie/mcp/admin-tools.ts - create_chapter tool for Addie

Frontend

• admin-events.html - Attendee Group section with create/view functionality
• admin-working-groups.html - 'event' type filter and badge

Test plan

• TypeScript builds without errors
• All 144 unit tests pass
• Admin Events page loads and displays event group section
• Admin Working Groups page shows 'event' filter option
• SQL injection prevented in chapter lookup (LIKE patterns escaped)
• UUID validation on event group endpoints

🤖 Generated with Claude Code