Add a data-driven QQ group chat surface

[caoergou]

Summary

• make the classic 群/校友录 route open a real QQ2006-style group chat
• resolve group identity, members, and authored history from mounted QQArchiveConversation(kind: 'group') data
• keep newly composed messages session-local so the read-only archive remains authoritative
• expose message history directly from the main panel and from the group window
• persist group/archive routing with serializable component props and emit a stable ui:action
• document the authoring path and cover routing plus browser behavior

Root cause

The main QQ panel rendered group, recent-contact, and message-manager controls as inert decoration. Although content packs could already declare group conversations in a QQ archive, the client had no group-chat view or route connecting those conversations to the panel. The archive manager was therefore the only usable history surface and remained hidden behind the menu.

Impact

Hosts can now mount a group conversation as data and reach it without forking React components. The social chat surface and the forensic archive stay separate: the group window supports local composition, while the archive remains read-only and searchable.

Validation

• npm run lint
• npm run typecheck:strict
• npx vitest run --maxWorkers=1 --minWorkers=1 --silent — 89 files, 868 tests passed
• PW_CHROMIUM_PATH=/opt/google/chrome/chrome npx playwright test e2e/qq.spec.ts --project=chromium --workers=1 — 13 passed
• npm run build:lib
• npm run size:check

Closes #311