Add Railiance Stage 1 run command

tools/README_tools.md

@@ -59,6 +59,10 @@ This model emphasizes:
 
 ---
 
+### `railiance-run`
+- Executes Stage 1 local validation from `railiance/app.toml`.
+- Emits a `railiance.run-result.v1` JSON result without command logs or secrets.
+
 ### `create_railiance_overlay_repo.sh`
 - Scaffolds a local Railiance overlay repo for a third-party upstream app.
 - Records upstream identity without vendoring upstream code.