Audit and adopt Remix v3 Beta 5 improvements

[kentcdodds]

Summary

• documents a repository-specific Remix v3 Beta 5 adoption audit with prioritized follow-up opportunities
• applies remix/ui/checkbox to the existing login and admin checkbox controls and standardizes the cookie import on remix/cookie
• minifies production client and MCP app bundles, matching the relevant Beta 5 template improvement
• updates MCP bundle assertions to validate stable behavior/protocol markers after minification
• records why trustProxy, Node production starts, and Frame resolution do not apply to the current Cloudflare Workers topology

Testing

• pre-commit typecheck passed for every commit
• bun run test:e2e: 20 passed
• bun run test:mcp: 4 passed

Review guidance

• Start with docs/agents/remix/beta-5-adoption-audit.md for the findings and prioritization.
• The UI behavior change is intentionally limited to three native checkboxes.
• The production build change only adds esbuild minification; development watchers remain unchanged.