docs: refresh engineering runbooks

[cursor]

Summary

• Updated existing engineering docs for event loader contracts, release automation, command/context-menu registration, Prisma generation, and configuration pitfalls.
• Corrected feature and command docs for ticket setup, Join-to-Create availability, /rank info requirements, and rank-card presence behavior.
• Refreshed architecture/database/contributing references for context-menu deployment, JTC schema/runtime mismatch, and current regression-test coverage.

Codepaths Covered

• src/handlers/events.js, src/events/Guild/*, src/events/validations/*
• .github/workflows/release.yml
• src/example.config.js, src/events/ready/registerCommands.js, src/events/ready/registerContextMenus.js
• src/commands/slash/General/rank.js, src/utils/rankCardPresenceStatus.js
• src/commands/slash/Management/setup.js, src/components/selects/setupSSM.js, ticket/JTC handlers, prisma/schema.prisma

Key Knowledge Gaps Addressed

• Removed stale event-loader caveats and release version-diff wording.
• Clarified there is no Prisma postinstall, npm run dev expects nodemon, and PRODUCTION=false still selects MONGODB_URI for runtime MongoDB URI unless config is adjusted.
• Documented that /setup currently exposes Welcome and Ticket only, ticket setup does not auto-post a panel, and JTC requires an existing setup record or future setup flow.

Verification

• git diff --check HEAD~1..HEAD
• npm test (37 tests passed)