Initialize Rust project with Cargo, dependencies, and module skeleton

Set up single-binary reverse-proxy project with all core dependencies
(axum, tokio, hyper, tower, rustls, tokio-rustls, rustls-acme, serde,
toml, arc-swap, tracing, tracing-subscriber, rustls-pemfile,
rustls-pki-types, clap, signal-hook, anyhow, thiserror) pinned to exact
versions. Create module skeleton (config, proxy, tls, rate_limit,
logging, admin, health, shutdown) matching architecture spec.

src/config/dynamic_config.rs

@@ -0,0 +1,50 @@
+use serde::Deserialize;
+
+#[allow(dead_code)]
+#[derive(Debug, Deserialize, Clone)]
+pub struct DynamicConfig {
+    pub sites: Vec<SiteConfig>,
+    pub rate_limit: RateLimitConfig,
+    pub body: BodyConfig,
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Deserialize, Clone)]
+pub struct SiteConfig {
+    pub host: String,
+    pub upstream: String,
+    #[serde(default = "default_upstream_scheme")]
+    pub upstream_scheme: String,
+    #[serde(default = "default_connect_timeout")]
+    pub upstream_connect_timeout_secs: u64,
+    #[serde(default = "default_request_timeout")]
+    pub upstream_request_timeout_secs: u64,
+}
+
+#[allow(dead_code)]
+fn default_upstream_scheme() -> String {
+    "http".to_string()
+}
+
+#[allow(dead_code)]
+fn default_connect_timeout() -> u64 {
+    5
+}
+
+#[allow(dead_code)]
+fn default_request_timeout() -> u64 {
+    60
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Deserialize, Clone)]
+pub struct RateLimitConfig {
+    pub requests_per_second: u32,
+    pub burst: u32,
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Deserialize, Clone)]
+pub struct BodyConfig {
+    pub limit_bytes: u64,
+}