Add run_tests.sh test runner script

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

run_tests.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# T YouTube Automated Test Runner Script
+set -e
+
+DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+echo "=== Setting up Python Virtual Environment ==="
+if [ ! -d "$DIR/backend/.venv" ]; then
+    python3 -m venv "$DIR/backend/.venv"
+fi
+
+echo "=== Installing Dependencies ==="
+"$DIR/backend/.venv/bin/pip" install -q -r "$DIR/backend/requirements.txt"
+
+echo "=== Executing Test Suite ==="
+"$DIR/backend/.venv/bin/python3" -m pytest "$DIR/backend/tests/"