feat(hooks): implement directory-agents-injector hook

src/hooks/directory-agents-injector/constants.ts

@@ -0,0 +1,9 @@
+import { join } from "node:path";
+import { xdgData } from "xdg-basedir";
+
+export const OPENCODE_STORAGE = join(xdgData ?? "", "opencode", "storage");
+export const AGENTS_INJECTOR_STORAGE = join(
+  OPENCODE_STORAGE,
+  "directory-agents",
+);
+export const AGENTS_FILENAME = "AGENTS.md";