Update dependencies and refactor application structure

- Updated various dependencies in `Cargo.toml` to their latest versions, including `tonic`, `tokio`, and `url`.
- Refactored `ServerConfig` to include a new `grpc_target` field, replacing the previous bind and port fields.
- Removed the `routes.rs` file and integrated its functionality into the main application logic.
- Enhanced the `PrinterInfo` struct to include additional fields for printer details.
- Simplified the main application flow by directly using the `ControlService` for handling requests.
- Cleaned up unused code and improved overall organization of the project structure.

proto/control.proto

@@ -0,0 +1,82 @@
+syntax = "proto3";
+
+package control.v1;
+
+service Control {
+  rpc ControlStream(stream ClientMessage) returns (stream ServerMessage);
+}
+
+message ClientMessage {
+  oneof msg {
+    Hello hello = 1;
+    PrintResult result = 2;
+    Pong pong = 3;
+    PrinterUpdate printers = 4;
+  }
+}
+
+message ServerMessage {
+  oneof msg {
+    PrintInstruction print = 1;
+    Ping ping = 2;
+  }
+}
+
+message Hello {
+  string client_id = 1;
+  string version = 2;
+  string hostname = 3;
+  repeated PrinterInfo printers = 4;
+}
+
+message Ping {
+  string nonce = 1;
+}
+
+message Pong {
+  string nonce = 1;
+}
+
+message PrintInstruction {
+  string request_id = 1;
+  bytes pdf_data = 2;
+  PrintParams params = 3;
+}
+
+message PrintParams {
+  uint32 copies = 1;
+  string duplex = 2;        // one_sided, long_edge, short_edge
+  string color = 3;         // auto, color, monochrome
+  string media = 4;
+  string quality = 5;       // draft, normal, high
+  string orientation = 6;   // portrait, landscape
+  string job_name = 7;
+  string printer = 8;
+}
+
+message PrintResult {
+  string request_id = 1;
+  bool ok = 2;
+  string printer = 3;
+  string message = 4;
+  uint32 retries_used = 5;
+}
+
+message PrinterUpdate {
+  repeated PrinterInfo printers = 1;
+}
+
+message PrinterInfo {
+  string id = 1;
+  string name = 2;
+  string host = 3;
+  string uri = 4;
+  string state = 5;
+  bool accepting_jobs = 6;
+  bool color_supported = 7;
+  uint32 active_jobs = 8;
+  uint32 ppm = 9;
+  uint32 ppm_color = 10;
+  repeated string reasons = 11;
+}
+