chore: clean Rust warnings and remove unused deps

- Remove serde_yaml and tokio from Cargo.toml (unused)
- Add #[allow(dead_code)] to utility code kept for future use
  (CUT_FULL, ALIGN_RIGHT, line(), PrinterError, SupabaseError,
   atualizar_sync, remover, Lock variant)
- Zero compiler warnings on release build

src-tauri/src/plugins/escpos.rs

@@ -8,6 +8,7 @@ pub const LF: &[u8] = b"\x0A";
 /// Cortar papel (parcial)
 pub const CUT: &[u8] = b"\x1D\x56\x01";
 /// Cortar papel (total)
+#[allow(dead_code)]
 pub const CUT_FULL: &[u8] = b"\x1D\x56\x00";
 /// Alimentar 3 linhas antes de cortar
 pub const FEED_CUT: &[u8] = b"\x1B\x64\x03";
@@ -17,6 +18,7 @@ pub const BOLD_OFF: &[u8] = b"\x1B\x45\x00";
 /// Alinhamento
 pub const ALIGN_LEFT: &[u8] = b"\x1B\x61\x00";
 pub const ALIGN_CENTER: &[u8] = b"\x1B\x61\x01";
+#[allow(dead_code)]
 pub const ALIGN_RIGHT: &[u8] = b"\x1B\x61\x02";
 /// Fonte normal / dupla
 pub const FONT_NORMAL: &[u8] = b"\x1B\x21\x00";
@@ -38,6 +40,7 @@ pub fn title(text: &str) -> Vec<u8> {
 }
 
 /// Monta linha normal (alinhada à esquerda)
+#[allow(dead_code)]
 pub fn line(text: &str) -> Vec<u8> {
     let mut out = Vec::new();
     out.extend_from_slice(ALIGN_LEFT);