Richer player profiles, launcher command guide, integration docs

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DjMbLQujBHunCCu5GpsHaT

panel/server/src/db.rs

@@ -672,6 +672,10 @@ const MIGRATIONS: &[&str] = &[
     r#"
     ALTER TABLE groups ADD COLUMN discord_role TEXT NOT NULL DEFAULT '';
     "#,
+    // Profile cosmetics.
+    r#"
+    ALTER TABLE user_profiles ADD COLUMN accent_color TEXT;
+    "#,
     // Servers can share one economy (balances and guild banks) by sharing a group name.
     r#"
     ALTER TABLE game_servers ADD COLUMN economy_group TEXT NOT NULL DEFAULT '';