chore: add bin/ci script for linter + unit tests

Simple pre-push verification: runs standardrb linter then unit tests.
Exits on first failure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pftg

bin/ci

@@ -0,0 +1,13 @@
+#!/bin/bash
+set -e
+
+echo "Running linter..."
+if ! bin/standardrb; then
+  echo "Lint errors found. Auto-fixing..."
+  bin/standardrb -a
+  echo "Lint errors were auto-fixed. Please review and re-commit."
+  exit 1
+fi
+
+echo "Running unit tests..."
+bin/rake test:unit