fix(check): skip exported config for formatters when workspace file exists

For formatters, the exported config was always symlinked into the
staging area since it starts empty, effectively ignoring any
pre-existing file in the workspace root. This was inconsistent with
linter behavior, where a pre-existing workspace file takes precedence.

Now check if the file already exists in the workspace root before
symlinking the exported config into the staging area. If it does,
skip the exported config so the workspace file is used instead,
matching the linter behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: marschattha

qlty-check/src/executor.rs

@@ -316,13 +316,19 @@ impl Executor {
 
         // load exported config paths before anything else
         for config_file in &exported_config_paths {
+            let file_name = config_file.file_name().unwrap();
+            let workspace_file = self.plan.workspace.root.join(file_name);
+
             if self.plan.workspace.root != self.plan.staging_area.destination_directory {
-                // for formatters
-                if let Some(path) = load_config_file_from_source(
-                    config_file,
-                    &self.plan.staging_area.destination_directory,
-                )? {
-                    loaded_config_files.push(path);
+                // for formatters: skip if the file already exists in the workspace root
+                // so that the user's config takes precedence, consistent with linter behavior
+                if !workspace_file.exists() {
+                    if let Some(path) = load_config_file_from_source(
+                        config_file,
+                        &self.plan.staging_area.destination_directory,
+                    )? {
+                        loaded_config_files.push(path);
+                    }
                 }
             }