fix(group-chat): glow the complete room avatar

[wtj-0527]

Summary

• glow the complete Group Chat room-list composite when any visible or hidden Agent is running
• follow the room avatar's rounded-square silhouette while preserving circular in-room Agent glows
• reuse the established Direct Chat / Group Chat four-second rainbow palette and reduced-motion fallback

Closes #2700

Validation

• npm run test -- tests/client/group-room-agent-avatar.test.ts tests/client/group-chat-panel-workspace-source.test.ts
• HERMES_VISUAL_EVIDENCE_DIR=/tmp/hermes-avatar-glow-evidence npx playwright test tests/e2e/group-chat-room-deeplink.spec.ts --grep "active runs glow the complete room avatar"
• npm run harness:check
• npm run build
• git diff --check

Visual evidence

• idle room composite: no glow
• active room composite: one rounded-square outer glow around the complete avatar
• active in-room Agent: circular outer glow using the same rainbow animation phase