update template links

[adhami3310]

and does some other modifications

[greptile-apps]

Greptile Summary

This PR refactors Reflex's template and build service integration by removing deprecated functionality and updating documentation links. The changes consolidate MCP (Model Context Protocol) documentation and simplify the template discovery system.

Key changes made:

1. MCP Documentation Restructuring: The comprehensive 97-line MCP_README file was completely emptied and replaced with a minimal MCP_README.md file that contains only a brief description and redirects users to external documentation at reflex.dev.

2. Template System Simplification: Updated REFLEX_TEMPLATES_URL from pointing to a dynamic service (https://reflex.dev/templates) to documentation-based templates (https://reflex.dev/docs/getting-started/open-source-templates/), indicating a shift from programmatic template fetching to documentation-driven discovery.

3. Build Service Integration Cleanup: Removed the classproperty utility and all associated dynamic URL generation methods (REFLEX_BUILD_URL, REFLEX_BUILD_POLL_URL, REFLEX_BUILD_CODE_URL). Updated REFLEX_BUILD_FRONTEND from https://reflex.build to https://build.reflex.dev, suggesting a domain migration.

4. Environment Variables Removal: Removed REFLEX_BUILD_FRONTEND and REFLEX_BUILD_BACKEND from the configurable environment variables, though the underlying constants remain accessible internally.

5. Dependency Cleanup: Removed the PACKAGE_LOCK constant and simplified imports by removing unused utilities.

These changes integrate with Reflex's broader architecture by moving away from complex dynamic service integrations toward a simpler, documentation-centric approach for template discovery and user guidance.

PR Description Notes:

• The PR body is extremely brief ("and does some other modifications") and doesn't adequately describe the significant changes being made, particularly the MCP documentation restructuring and build service integration removal.

Confidence score: 3/5

• This PR appears safe to merge but involves significant architectural changes that may need validation.
• The score reflects concerns about incomplete documentation migration (empty MCP_README file) and potential breaking changes for code relying on removed environment variables.
• Files needing attention: MCP_README (empty file should be removed), reflex/environment.py and reflex/constants/base.py (verify no dependent code is broken by removed constants).

_{4 files reviewed, 1 comment}

_{Edit Code Review Bot Settings | Greptile}

[greptile-apps]

style: The phrase 'This server is deployed and ready to use' may be confusing - clarify whether users need to deploy it themselves or if it's a hosted service

[masenf]

should we remove the reflex init link to the AI builder since it's not generally available?

[codspeed-hq]

CodSpeed Performance Report

Merging #5652 will not alter performance

_{Comparing update-template-links (a2f8f88) with main (5161944)}

Summary

✅ 8 untouched benchmarks

[adhami3310]

should we remove the reflex init link to the AI builder since it's not generally available?

i think the link is probably fine for now