Initial project setup with env template and gitignore

- .gitignore: Java/Maven, Node.js, IDE, OS, credentials
- .env.sample: backend + frontend environment variable template
- README.md: project overview and getting started guide
- CLAUDE.md: development rules and guidelines
- docs/: SUNDOL spec and design patterns guide

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,69 @@
+# ========================
+# Environment / Secrets
+# ========================
+.env
+.env.local
+.env.production
+.env.*.local
+
+# ========================
+# Java / Maven (Backend)
+# ========================
+target/
+*.class
+*.jar
+*.war
+*.ear
+*.log
+hs_err_pid*
+
+# Maven wrapper
+.mvn/wrapper/maven-wrapper.jar
+
+# ========================
+# Node.js (Frontend)
+# ========================
+node_modules/
+.next/
+out/
+build/
+dist/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# ========================
+# IDE
+# ========================
+.idea/
+*.iml
+*.iws
+.vscode/
+*.swp
+*.swo
+*~
+
+# ========================
+# OS
+# ========================
+.DS_Store
+Thumbs.db
+
+# ========================
+# OCI / Cloud credentials
+# ========================
+.oci/
+Wallet_*/
+*.pem
+*.key
+
+# ========================
+# Docker
+# ========================
+oracle_data/
+
+# ========================
+# Claude Code
+# ========================
+.claude/