fix(test): keep tests out of the user's config folder

Tests resolved the real per-user config dir. When the alias table
version moved, parallel tests migrated and rewrote the user's alias
file concurrently and one left it holding a single alias. Under test,
config_dir() is a per-process temp folder and the alias table comes
from the shipped defaults with no file I/O.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/config.rs

@@ -10,6 +10,13 @@ use std::path::PathBuf;
 /// file name onto it and `create_dir_all` its parent before writing.
 #[cfg(not(target_arch = "wasm32"))]
 pub fn config_dir() -> Option<PathBuf> {
+    // Tests must never read or write the person's real settings: a test run
+    // once raced dozens of tests through an alias-table migration and left the
+    // user's alias file holding a single line. Every store routes through here,
+    // so one per-process scratch folder isolates them all.
+    if cfg!(test) {
+        return Some(std::env::temp_dir().join(format!("ocs-test-config-{}", std::process::id())));
+    }
     let base: PathBuf = if cfg!(target_os = "windows") {
         std::env::var_os("APPDATA").map(PathBuf::from)?
     } else if cfg!(target_os = "macos") {