Monorepo Integration: Unified Backend, Frontend & Documentation

- Reorganize project into monorepo structure
  - backend/app/ - New FastAPI backend (modular with src/)
  - backend/legacy/ - Legacy database modules (relational & vector)
  - frontend/ - React text editor application

- Add launcher.py for easy full-stack startup
- Complete documentation in README.md
  - Quick start guide
  - API endpoints reference
  - Development setup
  - Troubleshooting

- Refactor main.py to 35 lines (app configuration only)
- Update .gitignore for full-stack project
- Add CHANGELOG.md with version history (v0.1.0-v0.1.1)

Structure is now clean and ready for team collaboration.

backend/app/pyproject.toml

@@ -0,0 +1,19 @@
+[project]
+name = "archivium-backend"
+version = "0.1.0"
+description = "Local archive encryption and authentication system"
+requires-python = ">=3.9,<3.13"
+dependencies = [
+    "fastapi>=0.104.0",
+    "uvicorn[standard]>=0.24.0",
+    "pydantic>=2.5.0",
+    "sqlalchemy>=2.0.0",
+    "passlib[argon2]>=1.7.4",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=7.0.0",
+    "pytest-asyncio>=0.21.0",
+    "httpx>=0.25.0",
+]