feat: Add Bookys scraper alongside EBoek with startup mode chooser

Adds a second scraper for bookys-ebooks.com that harvests direct 1fichier
download URLs into a .txt file. The existing EBoek scraper core is unchanged;
only the GUI gained a Mode menu entry to switch between the two.

Bookys specifics:
- Visible (never headless) browser, since the site is behind Cloudflare.
  The challenge is auto-detected: the scraper polls for real listing items
  and continues on its own once it clears, no button needed.
- Persistent Chrome profile in ~/.eboek_scraper/bookys_chrome_profile so the
  Cloudflare clearance cookie survives between runs. Removed the hardcoded
  user-agent override, which claimed Chrome/120 against a real Chrome/150 and
  invalidated that cookie on every launch.
- Pop-up ads are avoided by never clicking host links: hrefs are read and
  navigated to directly, with window.open neutered via CDP as a backstop.
- Host links are read with textContent rather than Selenium's .text, which
  returns empty for these elements because they sit in a collapsed container.
- Only 1fichier hosts are followed; other hosts on a page are ignored.

Build configs list the new modules as hidden imports in all four places.
gui_main imports the Bookys window lazily, so PyInstaller's static analysis
would otherwise miss it and the .exe would crash on switching modes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NVJc2XuTvqBHSuqotetseS

scripts/eboek_scraper.spec

@@ -6,7 +6,7 @@ a = Analysis(
     pathex=[],
     binaries=[],
     datas=[],
-    hiddenimports=['PyQt5.QtCore', 'PyQt5.QtGui', 'PyQt5.QtWidgets', 'selenium', 'selenium.webdriver', 'selenium.webdriver.chrome', 'selenium.webdriver.chrome.options', 'selenium.webdriver.common.by', 'core.scraper', 'core.scraper_thread', 'core.credentials', 'gui.main_window', 'gui.login_dialog', 'gui.progress_dialog', 'utils.validators'],
+    hiddenimports=['PyQt5.QtCore', 'PyQt5.QtGui', 'PyQt5.QtWidgets', 'selenium', 'selenium.webdriver', 'selenium.webdriver.chrome', 'selenium.webdriver.chrome.options', 'selenium.webdriver.common.by', 'core.scraper', 'core.scraper_thread', 'core.credentials', 'gui.main_window', 'gui.login_dialog', 'gui.progress_dialog', 'utils.validators', 'core.bookys_scraper', 'core.bookys_thread', 'gui.bookys_window', 'gui.startup_dialog'],
     hookspath=[],
     hooksconfig={},
     runtime_hooks=[],