Ensure context servers are spawned in the workspace directory (#35271)

This fixes an issue where we were not setting the context server working
directory at all.

Release Notes:

- Context servers will now be spawned in the currently active project
root.

---------

Co-authored-by: Danilo Leal <danilo@zed.dev>

crates/context_server/src/transport/stdio_transport.rs

@@ -1,3 +1,4 @@
+use std::path::PathBuf;
 use std::pin::Pin;
 
 use anyhow::{Context as _, Result};
@@ -22,7 +23,11 @@ pub struct StdioTransport {
 }
 
 impl StdioTransport {
-    pub fn new(binary: ModelContextServerBinary, cx: &AsyncApp) -> Result<Self> {
+    pub fn new(
+        binary: ModelContextServerBinary,
+        working_directory: &Option<PathBuf>,
+        cx: &AsyncApp,
+    ) -> Result<Self> {
         let mut command = util::command::new_smol_command(&binary.executable);
         command
             .args(&binary.args)
@@ -32,6 +37,10 @@ impl StdioTransport {
             .stderr(std::process::Stdio::piped())
             .kill_on_drop(true);
 
+        if let Some(working_directory) = working_directory {
+            command.current_dir(working_directory);
+        }
+
         let mut server = command.spawn().with_context(|| {
             format!(
                 "failed to spawn command. (path={:?}, args={:?})",