feat: project skeleton, CLI surface, generate command, secret redaction, and CI matrix

- Create Rust binary crate with clap CLI (listen, connect, generate, version)
- Implement generate command: CA/server/client certs, auth token, config.json
- Strict secret redaction: Redacted type, PEM/token/config redaction utilities
- Configurable addresses and ports with validation (fails before sockets open)
- GitHub Actions CI matrix: Windows/Linux/macOS with fmt, clippy, test, build,
  release-build, and smoke check jobs
- 39 unit tests covering CLI parsing, redaction, config, and credential generation
- Cross-platform safe paths and clean-room implementation

Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "rustunnel"
+version = "0.1.0"
+edition = "2024"
+description = "Cross-platform HTTPS mTLS lab/dev tunneling tool"
+license = "MIT"
+readme = "README.md"
+
+[dependencies]
+clap = { version = "4", features = ["derive"] }
+tokio = { version = "1", features = ["full"] }
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+anyhow = "1"
+thiserror = "1"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+rcgen = "0.14"
+x509-parser = "0.16"
+time = { version = "0.3", features = ["formatting"] }
+rand = "0.8"
+hex = "0.4"
+
+[dev-dependencies]
+tempfile = "3"