Add env var for worker path

Author: mattfbacon

crates/bot/src/worker.rs

@@ -120,12 +120,13 @@ struct Process {
 
 impl Process {
 	async fn spawn() -> anyhow::Result<Self> {
-		let child = std::process::Command::new("./worker")
+		let worker_path = std::env::var_os("TYPST_BOT_WORKER_PATH").unwrap_or_else(|| "./worker".into());
+		let child = std::process::Command::new(&worker_path)
 			.stdin(Stdio::piped())
 			.stdout(Stdio::piped())
 			.stderr(Stdio::inherit())
 			.spawn()
-			.context("spawning worker process.\n\nthis is likely because you are trying to run the bot from a checkout of the repo and `worker` is a directory. you can fix this by changing the path to the worker binary to point to the worker binary in the cargo target directory. alternatively, follow the instructions in the README that describe how to set up a standalone installation.")?;
+			.with_context(|| format!("spawning worker process (path={worker_path:?}).\n\ntry setting TYPST_BOT_WORKER_PATH to point to the worker binary, e.g. in the cargo target directory. alternatively, follow the instructions in the README that describe how to set up a standalone installation.")?;
 
 		let mut ret = Self { child: Some(child) };
 		// Ask for the version and ignore it, as a health check.