refactor(server): extract shared runtime and implement service install/run in arbiter-server.exe

server/crates/arbiter-proto/src/lib.rs

@@ -2,6 +2,10 @@ pub mod transport;
 pub mod url;
 
 use base64::{Engine, prelude::BASE64_STANDARD};
+use std::{
+    path::PathBuf,
+    sync::{LazyLock, RwLock},
+};
 
 pub mod proto {
     tonic::include_proto!("arbiter");
@@ -27,8 +31,26 @@ pub struct ClientMetadata {
 }
 
 pub static BOOTSTRAP_PATH: &str = "bootstrap_token";
+static HOME_OVERRIDE: LazyLock<RwLock<Option<PathBuf>>> = LazyLock::new(|| RwLock::new(None));
+
+pub fn set_home_path_override(path: Option<PathBuf>) -> Result<(), std::io::Error> {
+    let mut lock = HOME_OVERRIDE
+        .write()
+        .map_err(|_| std::io::Error::other("home path override lock poisoned"))?;
+    *lock = path;
+    Ok(())
+}
 
 pub fn home_path() -> Result<std::path::PathBuf, std::io::Error> {
+    if let Some(path) = HOME_OVERRIDE
+        .read()
+        .map_err(|_| std::io::Error::other("home path override lock poisoned"))?
+        .clone()
+    {
+        std::fs::create_dir_all(&path)?;
+        return Ok(path);
+    }
+
     static ARBITER_HOME: &str = ".arbiter";
     let home_dir = std::env::home_dir().ok_or(std::io::Error::new(
         std::io::ErrorKind::PermissionDenied,