refactor: purge Node.js, Rust is the one true backend

- Moved boosapi-rs/* to repo root
- Deleted all Node.js source (src/server/, src/web/, scripts/)
- Deleted node_modules, package.json, tsconfig, vite.config
- Updated .gitignore and AGENTS.md for Rust-only stack
- Fixed static file path for frontend dist/web/
- Dockerfile stays the same (already Rust-only)
- Kept dist/web/ for Rust static serving

src/config.rs

@@ -0,0 +1,57 @@
+use figment::{
+    providers::{Env, Format, Toml},
+    Figment,
+};
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct AppConfig {
+    pub server: ServerConfig,
+    pub db: DbConfig,
+    pub auth: AuthConfig,
+    pub proxy: ProxyConfig,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct ServerConfig {
+    pub host: String,
+    pub port: u16,
+    pub log_level: String,
+    pub cors_origins: Vec<String>,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct DbConfig {
+    pub url: String,
+    pub max_connections: u32,
+    pub ssl: bool,
+    pub runtime_db_url: Option<String>,
+    pub runtime_db_dialect: Option<String>,
+    pub runtime_db_ssl: Option<bool>,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct AuthConfig {
+    pub jwt_secret: String,
+    pub jwt_expiry_hours: i64,
+    pub auth_token: String,
+    pub proxy_token: String,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct ProxyConfig {
+    pub upstream_timeout_secs: u64,
+    pub first_byte_timeout_secs: u64,
+    pub max_retries: u32,
+    pub proxy_log_retention_days: u32,
+}
+
+impl AppConfig {
+    pub fn load() -> anyhow::Result<Self> {
+        dotenvy::dotenv().ok();
+        Ok(Figment::new()
+            .merge(Toml::file("config.toml").nested())
+            .merge(Env::prefixed("BOOSAPI_").split("__"))
+            .extract()?)
+    }
+}