feat!: v0.2.0 — ping-on-connect validation, try_connect, publish polish

- Add ping-on-connect handshake: all connect functions validate the device
  within 200ms, rejecting non-DongLoRa serial devices immediately
- Add try_connect() — non-blocking connect that errors instead of blocking
  forever when no USB device is present
- Add payload size validation in transmit() (max 256 bytes)
- Add ErrorCode: impl std::error::Error
- Fix drain_rx error handling (no longer swallows original error)
- Fix repository URL to github.com/donglora/client-rs
- Remove wire-level tag constants from top-level re-exports
- Add rust-version (MSRV 1.85), homepage, exclude fields to Cargo.toml
- Add examples/ping.rs
- Allow clippy unwrap/expect in test modules

Cargo.toml

@@ -1,13 +1,16 @@
 [package]
 name = "donglora-client"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2024"
+rust-version = "1.85"
 authors = ["Stephen Waits <steve@waits.net>"]
 license = "MIT"
 description = "DongLoRa host library — connect, configure, send/receive LoRa packets"
-repository = "https://github.com/swaits/donglora"
+repository = "https://github.com/donglora/client-rs"
+homepage = "https://github.com/donglora/client-rs"
 keywords = ["lora", "radio", "usb", "serial"]
 categories = ["hardware-support"]
+exclude = ["CLAUDE_TODO.md", "deny.toml", "justfile", "mise.toml", "rustfmt.toml", ".jj"]
 
 [dependencies]
 anyhow = "1"