add sub-bar usage widget extension with opencode-go support

pi/files/agent/extensions/sub-bar/src/paths.ts

@@ -0,0 +1,21 @@
+/**
+ * Shared path helpers for sub-bar settings storage.
+ */
+
+import { getAgentDir } from "@mariozechner/pi-coding-agent";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const SETTINGS_FILE_NAME = "pi-sub-bar-settings.json";
+
+export function getExtensionDir(): string {
+	return join(dirname(fileURLToPath(import.meta.url)), "..");
+}
+
+export function getSettingsPath(): string {
+	return join(getAgentDir(), SETTINGS_FILE_NAME);
+}
+
+export function getLegacySettingsPath(): string {
+	return join(getExtensionDir(), "settings.json");
+}