Strengthen determinism gates and add TUI v2 agent testing workflow

scripts/run_determinism_tests.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+timeout_bin="timeout"
+if ! command -v "$timeout_bin" >/dev/null 2>&1; then
+    if command -v gtimeout >/dev/null 2>&1; then
+        timeout_bin="gtimeout"
+    else
+        timeout_bin=""
+    fi
+fi
+
+pytest_args=(
+    -q
+    --maxfail=1
+    --determinism-only
+    src/tests
+)
+
+pytest_bin="pytest"
+if ! command -v "$pytest_bin" >/dev/null 2>&1; then
+    if [[ -x ".venv/bin/pytest" ]]; then
+        pytest_bin=".venv/bin/pytest"
+    else
+        echo "pytest not found on PATH and .venv/bin/pytest is missing" >&2
+        exit 2
+    fi
+fi
+
+if [[ -n "$timeout_bin" ]]; then
+    $timeout_bin 2m python3 scripts/check_determinism_suite.py \
+        --pytest-bin "$pytest_bin" \
+        --min-tests "${DETERMINISM_MIN_TESTS:-25}"
+    $timeout_bin 10m "$pytest_bin" "${pytest_args[@]}"
+else
+    echo "timeout command not found; running determinism tests without timeout" >&2
+    python3 scripts/check_determinism_suite.py \
+        --pytest-bin "$pytest_bin" \
+        --min-tests "${DETERMINISM_MIN_TESTS:-25}"
+    "$pytest_bin" "${pytest_args[@]}"
+fi