Initial commit — Stage 0 project foundation

- Cargo workspace with engine, editor, tests crates
- oxide-editor binary stub (builds and runs cleanly)
- install.sh for Linux system installation
- README.md with logo, build and install instructions
- GPLv3 LICENSE
- .gitignore

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,32 @@
+# Rust / Cargo
+/target/
+Cargo.lock
+
+# Editor and IDE
+.vscode/
+.idea/
+*.iml
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Environment / secrets
+.env
+.env.*
+
+# Build artifacts and packages
+*.deb
+*.rpm
+*.tar.gz
+*.zip
+
+# Logs
+*.log
+
+# Notes
+*.md
+!README.md