feat(rust): scaffold Rust workspace and fix TypeScript build errors

- Add @git.zone/tsrust with linux_amd64/linux_arm64 cross-compilation
- Scaffold Rust workspace with 5 crates: mailer-core, mailer-smtp, mailer-security, mailer-napi, mailer-bin
- Fix all TypeScript compilation errors for upgraded dependencies (smartfile v13, mailauth v4.13, smartproxy v23)
- Replace smartfile.fs/memory with @push.rocks/smartfs throughout codebase
- Fix .ts import extensions to .js for NodeNext module resolution
- Update DKIMSignOptions usage to match mailauth v4.13 API
- Add MTA error classes with permissive signatures for legacy SMTP client
- Replace removed DcRouter/StorageManager/deliverability imports with local interfaces

rust/crates/mailer-bin/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "mailer-bin"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "mailer-bin"
+path = "src/main.rs"
+
+[dependencies]
+mailer-core = { path = "../mailer-core" }
+mailer-smtp = { path = "../mailer-smtp" }
+mailer-security = { path = "../mailer-security" }
+tokio.workspace = true
+tracing.workspace = true
+serde.workspace = true
+serde_json.workspace = true

rust/crates/mailer-bin/src/main.rs

@@ -0,0 +1,11 @@
+//! mailer-bin: Standalone Rust binary for the @serve.zone/mailer network stack.
+
+fn main() {
+    println!(
+        "mailer-bin v{} (core: {}, smtp: {}, security: {})",
+        env!("CARGO_PKG_VERSION"),
+        mailer_core::version(),
+        mailer_smtp::version(),
+        mailer_security::version(),
+    );
+}

rust/crates/mailer-core/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "mailer-core"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+thiserror.workspace = true
+tracing.workspace = true
+bytes.workspace = true
+mailparse.workspace = true

rust/crates/mailer-core/src/lib.rs

@@ -0,0 +1,19 @@
+//! mailer-core: Email model, validation, and RFC 5322 primitives.
+
+/// Re-export mailparse for MIME parsing.
+pub use mailparse;
+
+/// Placeholder for email address validation and data types.
+pub fn version() -> &'static str {
+    env!("CARGO_PKG_VERSION")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_version() {
+        assert!(!version().is_empty());
+    }
+}

rust/crates/mailer-napi/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "mailer-napi"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+mailer-core = { path = "../mailer-core" }
+mailer-smtp = { path = "../mailer-smtp" }
+mailer-security = { path = "../mailer-security" }
+napi.workspace = true
+napi-derive.workspace = true
+tokio.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+
+[build-dependencies]
+napi-build = "2"

rust/crates/mailer-napi/build.rs

@@ -0,0 +1,5 @@
+extern crate napi_build;
+
+fn main() {
+    napi_build::setup();
+}

rust/crates/mailer-napi/src/lib.rs

@@ -0,0 +1,15 @@
+//! mailer-napi: N-API bindings exposing Rust mailer to Node.js/TypeScript.
+
+use napi_derive::napi;
+
+/// Returns the version of the native mailer module.
+#[napi]
+pub fn get_version() -> String {
+    format!(
+        "mailer-napi v{} (core: {}, smtp: {}, security: {})",
+        env!("CARGO_PKG_VERSION"),
+        mailer_core::version(),
+        mailer_smtp::version(),
+        mailer_security::version(),
+    )
+}

rust/crates/mailer-security/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "mailer-security"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+mailer-core = { path = "../mailer-core" }
+mail-auth.workspace = true
+ring.workspace = true
+thiserror.workspace = true
+tracing.workspace = true
+serde.workspace = true

rust/crates/mailer-security/src/lib.rs

@@ -0,0 +1,18 @@
+//! mailer-security: DKIM, SPF, and DMARC verification.
+
+pub use mailer_core;
+
+/// Placeholder for DKIM/SPF/DMARC implementation.
+pub fn version() -> &'static str {
+    env!("CARGO_PKG_VERSION")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_version() {
+        assert!(!version().is_empty());
+    }
+}

rust/crates/mailer-smtp/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "mailer-smtp"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+mailer-core = { path = "../mailer-core" }
+tokio.workspace = true
+tokio-rustls.workspace = true
+hickory-dns.workspace = true
+dashmap.workspace = true
+thiserror.workspace = true
+tracing.workspace = true
+bytes.workspace = true
+serde.workspace = true

rust/crates/mailer-smtp/src/lib.rs

@@ -0,0 +1,18 @@
+//! mailer-smtp: SMTP protocol engine (server + client).
+
+pub use mailer_core;
+
+/// Placeholder for the SMTP server and client implementation.
+pub fn version() -> &'static str {
+    env!("CARGO_PKG_VERSION")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_version() {
+        assert!(!version().is_empty());
+    }
+}