docs: refresh engineering runbooks

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Summary

• Updated existing engineering docs for current event-loader, interaction routing, command deployment, release automation, setup, database, and feature behavior.
• Corrected setup/configuration guidance for explicit npx prisma generate, external nodemon, PRODUCTION truthiness, and distinct DEV_GUILD_ID vs config.handler.guildId codepaths.
• Clarified partial or constrained feature paths for tickets, Join-to-Create, and manually managed rank/XP records.

Codepaths Covered

• src/handlers/events.js and src/events/validations/**
• src/events/Guild/interactionCreate.js, components.js, messageCreate.js, and jointocreate.js
• src/events/ready/registerCommands.js and registerContextMenus.js
• .github/workflows/release.yml
• src/example.config.js, src/handlers/prisma.js, prisma/schema.prisma
• /setup, ticket handlers, and /rank command implementation

Knowledge Gaps Addressed

• Removed stale caveats that Guild { event, run } handlers were not registered.
• Replaced outdated release version-line-diff wording with missing-tag gating.
• Documented the MongoDB PRODUCTION=false truthiness pitfall and the no-postinstall Prisma generation requirement.
• Synced contributor docs with current event-loader contracts and test inventory.

Validation

• git diff --check
• npm test (37 tests passing)