Simplify printer/ module for someone learning Rust

Drop reqwest, RPITIT+Send signature, and multi-variant error enum from the
teaching example so the only new idea per file is the trait override itself.
Real networking stays in adapters/, unaffected.

src/printer/bambu.rs

@@ -1,38 +1,24 @@
-use std::path::Path;
-
-use tracing::info;
-
 use super::{Printer, PrinterBase, PrinterError};
 
-/// Bambu-specific fields — this is the "extends GenericBambuPrinter" part of
-/// your original design, expressed as extra struct fields instead of a
-/// second inheritance layer.
 pub struct BambuPrinter {
     base: PrinterBase,
     pub access_code: String,
 }
 
 impl BambuPrinter {
-    pub fn new(id: impl Into<String>, name: impl Into<String>, host: impl Into<String>, access_code: impl Into<String>) -> Self {
+    pub fn new(id: &str, name: &str, host: &str, access_code: &str) -> Self {
         Self {
             base: PrinterBase { id: id.into(), name: name.into(), host: host.into() },
             access_code: access_code.into(),
         }
     }
 
-    /// A method that ONLY exists on `BambuPrinter` — not part of the
-    /// `Printer` trait at all. This is what "adding a printer-specific
-    /// method" looks like: just define it in this struct's own `impl`
-    /// block. `PrusaPrinter` and `KlipperPrinter` have no equivalent, and
-    /// calling this requires a `PrinterHandle::Bambu(..)` match first (see
-    /// the example), which is the price for not doing runtime downcasting.
-    ///
-    /// Real implementation lives in `adapters::bambu::dispatch_file` (FTPS
-    /// on port 990); this is the domain-model-facing wrapper around it.
-    pub async fn dispatch_gcode_ftp(&mut self, local_path: &Path, remote_name: &str) -> Result<(), PrinterError> {
-        info!(printer = %self.base.id, remote_name = %remote_name, path = ?local_path, "dispatching gcode over FTPS");
-        // See adapters::bambu::dispatch_file for the full FTPS upload.
-        Ok(())
+    /// Only `BambuPrinter` has this — it's not on the `Printer` trait at
+    /// all, so `PrusaPrinter`/`KlipperPrinter` simply don't have it. This
+    /// is what "adding a printer-specific method" looks like: just define
+    /// it in this struct's own `impl` block.
+    pub fn dispatch_gcode(&self, file_name: &str) {
+        println!("[{}] uploading {file_name} over FTPS", self.base.name);
     }
 }
 
@@ -41,14 +27,11 @@ impl Printer for BambuPrinter {
         &self.base
     }
 
-    /// OVERRIDE: Bambu speaks MQTTS on port 8883, authenticated with the
-    /// printer's LAN access code. Completely different transport from the
-    /// other two vendors below.
+    /// OVERRIDE: Bambu's real connect logic opens an MQTTS session (see
+    /// `adapters::bambu::run_telemetry` for that). Here we just print what
+    /// it would do, so the focus stays on how dispatch works.
     async fn connect(&mut self) -> Result<(), PrinterError> {
-        info!(printer = %self.base.id, host = %self.base.host, "connecting to Bambu printer over MQTTS:8883");
-        // Real implementation: open the MQTTS session and wait for the
-        // first `report` message — see adapters::bambu::run_telemetry,
-        // which this would delegate to once wired into the daemon.
+        println!("[{}] connecting over MQTT with access code {}", self.base.name, self.access_code);
         Ok(())
     }
 }