Fix build errors: FTPS AsyncRead bridge, TLS connector type, unsafe env::set_var, dead code

Verified with cargo check + cargo run --example printer_polymorphism.

src/main.rs

@@ -111,20 +111,8 @@ async fn main() -> anyhow::Result<()> {
     Ok(())
 }
 
-/// Loads a `.env` file if present, without pulling in a heavyweight config
-/// crate. No-op (and safe to ignore errors) when the file doesn't exist.
+/// Loads `.env` if present; a missing file is fine (env vars may already be
+/// set by the process supervisor), so the error is deliberately ignored.
 fn dotenvy_load() {
-    if let Ok(contents) = std::fs::read_to_string(".env") {
-        for line in contents.lines() {
-            let line = line.trim();
-            if line.is_empty() || line.starts_with('#') {
-                continue;
-            }
-            if let Some((key, value)) = line.split_once('=') {
-                if std::env::var(key).is_err() {
-                    std::env::set_var(key, value);
-                }
-            }
-        }
-    }
+    let _ = dotenvy::dotenv();
 }