fix(close): Edge fallback + better tryClose + honest hint

There is no JavaScript override for browser tab-close security:
``window.close()`` only succeeds on windows JS opened (Chrome --app
windows qualify; a regular browser tab does not). What we can do is
make the --app path easier to hit and the failure case more
actionable.

Three changes:

1. ``src/gui/__main__.py`` — extend browser detection. PATH lookup
   now also looks for ``msedge`` / ``microsoft-edge``; Windows install
   candidates include the Edge install path; macOS candidates include
   Edge and Chromium. Edge is Chromium-based, supports ``--app``, and
   ships on every Windows 10+ machine — so users without Chrome no
   longer fall through to the regular browser tab. When the fallback
   IS hit, print a warning to stderr explaining why Close-from-page
   will require Ctrl+W. Renamed ``_find_chrome`` to
   ``_find_app_browser`` to reflect the broader scope.

2. ``_FAREWELL_SCRIPT_TEMPLATE`` in ``components/_legacy.py`` —
   factor close attempts into a ``tryClose`` helper that runs three
   escalating tries: standard ``win.close()``, the
   ``win.open('', '_self')`` history-rewrite trick (no-op in modern
   Chrome but free), and ``win.top.close()``. Auto-close on paint AND
   the manual button now both call this helper. Skip the manual hint
   if the close eventually succeeded between the click and the 250 ms
   timeout.

3. ``quit.close_hint`` in en/es i18n packs — rewrite the message to
   tell the user honestly that this is a browser security restriction,
   tell them the Ctrl+W keystroke that works, and point them at
   ``python -m src.gui`` for the auto-closing app-mode experience.

2008 tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/i18n/packs/es.json

@@ -53,7 +53,7 @@
     "farewell_title": "DataTools se ha cerrado",
     "farewell_subtitle": "Ya puedes cerrar esta ventana.",
     "close_window_button": "Cerrar esta ventana",
-    "close_hint": "Tu navegador bloqueó el cierre. Presiona Ctrl+W (o ⌘W en Mac) para cerrar esta pestaña manualmente."
+    "close_hint": "Tu navegador está bloqueando el cierre — es una restricción de seguridad para pestañas que abriste tú mismo, no algo que podamos anular. Presiona Ctrl+W (o ⌘W en Mac) para cerrar esta pestaña. Ejecuta DataTools con python -m src.gui para tener una ventana de aplicación que se cierra sola."
   },
   "close_page": {
     "page_title": "DataTools — Cerrar",