fix: restore and stabilize tab navigation with Alpine.js

- Fixed navigation blockage by moving Alpine state to body scope
- Resolved CSS display conflicts between legacy .active class and x-show
- Synchronized legacy auth logic with Alpine global state
- Redirected legacy switchTab calls to Alpine events
- Removed obsolete tabs.js and updated home section initialization
- Added E2E navigation test placeholder

tests/e2e/test_navigation.py

@@ -0,0 +1,41 @@
+import pytest
+from playwright.sync_api import Page, expect
+
+# Since we don't have a full running environment with auth easily mockable in pure Python Playwright 
+# without starting the server, I will write a test that can be run if the server is up.
+# For CI/CD, we'd use a fixture to start the uvicorn server.
+
+@pytest.mark.skip(reason="Requires running server and complex auth mock")
+def test_tab_navigation(page: Page):
+    # Navigate to the app
+    page.goto("http://localhost:3000/web")
+    
+    # Mock authentication state in localStorage and Alpine
+    page.evaluate("""() => {
+        localStorage.setItem('auth_token', 'mock-token');
+        document.body.__x.$data.isAuthenticated = true;
+        document.body.__x.$data.username = 'TestUser';
+    }""")
+    
+    # Reload or wait for Alpine to react
+    page.reload()
+    
+    # Verify Home tab is active by default
+    expect(page.locator("#tab-home")).to_be_visible()
+    expect(page.locator("button.tab:has-text('Accueil')")).to_have_class(/active/)
+    
+    # Click on Anime tab
+    page.click("button.tab:has-text('Anime')")
+    
+    # Verify Anime tab is shown and Home is hidden
+    expect(page.locator("#tab-anime")).to_be_visible()
+    expect(page.locator("#tab-home")).to_be_hidden()
+    expect(page.locator("button.tab:has-text('Anime')")).to_have_class(/active/)
+    
+    # Click on Watchlist tab
+    page.click("button.tab:has-text('Watchlist')")
+    
+    # Verify Watchlist tab is shown
+    expect(page.locator("#tab-watchlist")).to_be_visible()
+    expect(page.locator("#tab-anime")).to_be_hidden()
+    expect(page.locator("button.tab:has-text('Watchlist')")).to_have_class(/active/)