fix: complete config path and review follow-ups (#3348)

packages/vscode/src/opencodeConfigPaths.ts

@@ -0,0 +1,8 @@
+import os from 'node:os';
+import path from 'node:path';
+
+// Resolve once at extension startup, matching the web backend.
+export const OPENCODE_CONFIG_DIR = path.join(
+  process.env.XDG_CONFIG_HOME?.trim() || path.join(os.homedir(), '.config'),
+  'opencode',
+);