Move Building Features files (Step 3)

Moved 14 files to building-features/:

Common Patterns (4):
- guides/hmr-and-hot-reloading-with-the-webpack-dev-server.md
- guides/i18n.md
- guides/rspec-configuration.md
- guides/minitest-configuration.md

Advanced Techniques (3):
- guides/streaming-server-rendering.md
- guides/how-to-conditionally-server-render-based-on-device-type.md
- guides/how-to-use-different-files-for-client-and-server-rendering.md

Integration Guides (4):
- javascript/react-router.md
- javascript/react-and-redux.md
- javascript/react-helmet.md
- guides/rails-webpacker-react-integration-options.md

Tools & Workflow (3):
- javascript/code-splitting.md
- javascript/images.md
- javascript/foreman-issues.md

All filenames kept as original (no renaming).

Part of IA redesign Phase 2, Step 3.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ihabadham