feat: ship Rust login manager and GitLab release pipeline

Replace the legacy Go implementation as the production path, quarantine the reference tree, add deterministic release packaging and version metadata, and run verification through GitLab CI.

Cargo.toml

@@ -0,0 +1,40 @@
+[workspace]
+members = [".", "crates/latchd-core", "crates/latchd-auth", "crates/latchd-tui"]
+resolver = "3"
+
+[workspace.package]
+version = "0.3.0"
+edition = "2024"
+rust-version = "1.88"
+license = "Apache-2.0"
+
+[package]
+name = "latchd"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+description = "A secure terminal login manager for Linux"
+license.workspace = true
+
+[[bin]]
+name = "latchd"
+path = "rust/main.rs"
+
+[dependencies]
+clap = { version = "4.5", features = ["derive", "env"] }
+color-eyre = "0.6"
+latchd-auth = { path = "crates/latchd-auth" }
+latchd-core = { path = "crates/latchd-core" }
+latchd-tui = { path = "crates/latchd-tui" }
+libc = "0.2"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
+
+[profile.release]
+opt-level = 3
+lto = "thin"
+codegen-units = 1
+debug = false
+incremental = false
+panic = "abort"
+strip = "symbols"