docs: add CLAUDE.md and TROUBLESHOOTING.md, fix npm install for Node.js v24

- Add CLAUDE.md with architecture overview and development guidance for Claude Code
- Add TROUBLESHOOTING.md with solutions for common development issues
- Fix npm install failures in WSL with Node.js v24 by using --openssl-legacy-provider
- Document Node.js v24 + OpenSSL 3.x WSL incompatibility and workarounds

The CLAUDE.md file provides future Claude Code instances with essential information about:
- Commands for testing and development
- Core architecture (engine.js, generator.js, template-v2 system)
- Key concepts (field mapping, placeholder mapping, layout constants)
- Common development tasks and patterns

The TROUBLESHOOTING.md file provides detailed solutions for:
- npm install SSL cipher errors in WSL environments
- CORS errors when loading timeline
- Template validation issues
- CSV data loading problems
- Test failures

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Makefile

@@ -29,7 +29,8 @@ help:
 # Development setup
 install:
 	@echo "Installing development dependencies..."
-	npm install
+	@# Workaround for Node.js v24 + OpenSSL 3.x in WSL (ERR_SSL_CIPHER_OPERATION_FAILED)
+	@export NODE_OPTIONS="--openssl-legacy-provider" && npm install
 	@echo "✅ Dependencies installed"
 
 # Testing targets