Quest system add weekly summary email via resend (follows pr #173 issue)

[clintjeff2]

Motivation

• Send weekly summaries to registered agents with email addresses summarizing quests completed, XP earned/level changes, leaderboard movement, and top badge.
• Respect per-agent opt-out and provide a cron/admin-triggered endpoint to call the job.
• Use Resend (sandbox key in tests) and ensure templates render both plain-text and HTML for 0-quest and multi-quest scenarios.

Description

• Add an admin-gated endpoint POST /api/admin/send-weekly-summary that enumerates registered agents, skips missing-email or opted-out agents, builds a weekly summary, and calls Resend to send the email (app/api/admin/send-weekly-summary/route.ts).
• Extend agent registry with optional email and emailOptOut fields and validate/normalize email on registration (lib/agent-registry.ts).
• Implement weekly summary aggregation and rendering (previous Sunday–Sunday window) producing plain-text and HTML templates with quests, XP, level changes, leaderboard rank movement, and top badge (lib/email/weekly-summary.ts).
• Add sendRawEmail helper using the RESEND_API_KEY env var and reuse existing Resend/react email flow (lib/email/resend.ts).
• Capture published system events in-memory so aggregation can inspect recent quest/xp/badge events and add helpers to list/reset events for tests (lib/events/system-events.ts).
• Add tests that mock the Resend client and verify send behavior, opt-out handling, authorization, and template rendering for 0-quest and 5+-quest scenarios (__tests__/api/weekly-summary.test.ts).

Testing

• Ran npm test -- __tests__/api/weekly-summary.test.ts and all tests in that file passed (4 tests passed).
• Ran npm test -- __tests__/api/weekly-summary.test.ts __tests__/api/registry/registry.test.ts and both test files passed (total tests passed).
• Type-checking with npx tsc --noEmit surfaced unrelated missing dependency errors (lru-cache, @wagmi/connectors) present in the repo and not introduced by this change, so full typecheck was not completed.
• Lint (npm run lint) reported existing unrelated lint issues elsewhere in the repo and did not block this change.

---

Closes #207

[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[clintjeff2]

@leocagli, review and merge. Loved this task.

[clintjeff2]

@leocagli, review and merge.

[clintjeff2]

@leocagli, review and merge.

[clintjeff2]

@leocagli, review and merge.

[clintjeff2]

@leocagli, please review and merge.