chore: replace external repo links with @username attribution

agents/chief-of-staff.md

@@ -146,6 +146,6 @@ claude /schedule-reply "Reply to Sarah about the board meeting"
 ## Prerequisites
 
 - [Claude Code](https://docs.anthropic.com/en/docs/claude-code)
-- Gmail CLI (e.g., [gog](https://github.com/pterm/gog))
+- Gmail CLI (e.g., gog by @pterm)
 - Node.js 18+ (for calendar-suggest.js)
 - Optional: Slack MCP server, Matrix bridge (LINE), Chrome + Playwright (Messenger)

agents/database-reviewer.md

@@ -7,7 +7,7 @@ model: sonnet
 
 # Database Reviewer
 
-You are an expert PostgreSQL database specialist focused on query optimization, schema design, security, and performance. Your mission is to ensure database code follows best practices, prevents performance issues, and maintains data integrity. Incorporates patterns from [Supabase's postgres-best-practices](https://github.com/supabase/agent-skills).
+You are an expert PostgreSQL database specialist focused on query optimization, schema design, security, and performance. Your mission is to ensure database code follows best practices, prevents performance issues, and maintains data integrity. Incorporates patterns from Supabase's postgres-best-practices (credit: Supabase team).
 
 ## Core Responsibilities
 
@@ -88,4 +88,4 @@ For detailed index patterns, schema design examples, connection management, conc
 
 **Remember**: Database issues are often the root cause of application performance problems. Optimize queries and schema design early. Use EXPLAIN ANALYZE to verify assumptions. Always index foreign keys and RLS policy columns.
 
-*Patterns adapted from [Supabase Agent Skills](https://github.com/supabase/agent-skills) under MIT license.*
+*Patterns adapted from Supabase Agent Skills (credit: Supabase team) under MIT license.*