feat(api): Add CLI flag and env var to enable test hooks

gui.py

@@ -14,6 +14,8 @@ import tomli_w
 import threading
 import time
 import math
+import sys
+import os
 from pathlib import Path
 from tkinter import filedialog, Tk
 import aggregate
@@ -393,6 +395,7 @@ def _parse_history_entries(history: list[str], roles: list[str] | None = None) -
 class App:
     def __init__(self):
         self.config = load_config()
+        self.test_hooks_enabled = '--enable-test-hooks' in sys.argv or os.environ.get('SLOP_TEST_HOOKS') == '1'
 
         # ---- global settings from config.toml ----
         ai_cfg = self.config.get("ai", {})