docs: refresh engineering runbooks

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Summary

• Updated setup/configuration docs to clarify explicit npx prisma generate, DEV_GUILD_ID vs handler.guildId, and the PRODUCTION=false MongoDB URI truthiness pitfall.
• Refreshed engineering and architecture docs for current event-loader behavior, context-menu deployment, release tag-existence gating, and regression-test coverage.
• Documented rank-card presence normalization, required /rank info <user>, ticket setup limitations, and current Join-to-Create WIP constraints.

Codepaths covered

• src/handlers/events.js, src/events/ready/registerCommands.js, src/events/ready/registerContextMenus.js
• .github/workflows/release.yml, package.json, src/example.config.js
• src/commands/slash/General/rank.js, src/utils/rankCardPresenceStatus.js
• src/commands/slash/Management/setup.js, src/components/selects/ticketSSM.js, src/components/selects/ticket-menu.js, src/events/Guild/jointocreate.js, prisma/schema.prisma
• Current tests/*.test.js regression inventory

Knowledge gaps addressed

• Removed stale event-loader caveat and release diff-gate wording.
• Made setup/runbook docs explicit about no Prisma postinstall hook.
• Clarified JTC and ticket setup limitations so operators do not expect missing UI/panel behavior.

Verification

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