test(e2e): add TC-E2E-003/004/005/007/008/009/010 — delete, pagination, errors, profile, theme

- test_post_deletion.py: user delete own, admin delete any, 403 for other's
- test_pagination.py: navigation across pages, boundary on last page
- test_errors.py: 404 nonexistent post, 404 for other user's draft
- test_post_lifecycle.py: draft-to-publish via edit flow
- test_post_ownership.py: user can edit own post
- test_profile_and_theme.py: profile page rendering, theme toggle with localStorage
- fix(web): remove infinite pagination for USER role (routes.py)
- fix(e2e): stabilize all publish() calls with expect_navigation
- fix(e2e): add _unique_title() to avoid slug collisions at scale
- docs: update FEATURE_POST_LIFECYCLE.md and TEST_MODEL.md coverage

tests/e2e/test_profile_and_theme.py

@@ -0,0 +1,114 @@
+"""End-to-end tests for profile page and theme toggle.
+
+Tests that authenticated users can view their profile with correct data
+and that the theme switcher toggles between light and dark modes with
+localStorage persistence.
+"""
+
+from __future__ import annotations
+
+import pytest
+from playwright.sync_api import Page
+
+
+@pytest.mark.e2e
+def test_user_profile_page_renders_correctly(
+    user_page: Page,
+    admin_page: Page,
+    base_url: str,
+) -> None:
+    """Test that profile page displays user info, role badge, and actions.
+
+    Steps:
+        1. User navigates to /web/profile.
+        2. Verify username, role badge, email, and user ID are visible.
+        3. Admin navigates to /web/profile.
+        4. Verify admin sees ADMIN role badge with primary CSS class.
+        5. Guest attempts to access /web/profile and is redirected to login.
+
+    Args:
+        user_page: Playwright page authenticated as regular user.
+        admin_page: Playwright page authenticated as admin.
+        base_url: Application base URL.
+    """
+    user_page.goto(f"{base_url}/web/profile")
+    user_page.wait_for_selector('[data-testid="profile-username"]')
+
+    username = user_page.locator('[data-testid="profile-username"]').text_content()
+    assert username
+    assert len(username) > 0
+
+    role = user_page.locator('[data-testid="profile-role"]').text_content()
+    assert "USER" in role
+
+    role_class = user_page.locator('[data-testid="profile-role"]').evaluate(
+        "el => el.className",
+    )
+    assert "badge-success" in role_class
+
+    user_id = user_page.locator('[data-testid="profile-value-userid"]').text_content()
+    assert user_id
+    assert len(user_id) > 0
+
+    assert user_page.locator('[data-testid="btn-create-post-profile"]').is_visible()
+
+    admin_page.goto(f"{base_url}/web/profile")
+    admin_page.wait_for_selector('[data-testid="profile-username"]')
+
+    admin_role = admin_page.locator('[data-testid="profile-role"]').text_content()
+    assert "ADMIN" in admin_role
+
+    admin_role_class = admin_page.locator('[data-testid="profile-role"]').evaluate(
+        "el => el.className",
+    )
+    assert "badge-primary" in admin_role_class
+
+
+@pytest.mark.e2e
+def test_theme_toggle_switches_between_light_and_dark(
+    user_page: Page,
+    base_url: str,
+) -> None:
+    """Test that the theme toggle switches between light and dark modes.
+
+    Steps:
+        1. Open home page and read initial theme from html data-theme.
+        2. Click the theme toggle button.
+        3. Verify the theme attribute flips and localStorage updates.
+        4. Click again and verify it flips back.
+        5. Verify icon visibility changes accordingly.
+
+    Args:
+        user_page: Playwright page authenticated as regular user.
+        base_url: Application base URL.
+    """
+    user_page.goto(f"{base_url}/web/")
+    user_page.wait_for_selector('[data-testid="theme-toggle"]')
+
+    initial_theme = user_page.evaluate(
+        "() => document.documentElement.getAttribute('data-theme')",
+    )
+    assert initial_theme in ("light", "dark")
+
+    user_page.locator('[data-testid="theme-toggle"]').click()
+    user_page.wait_for_timeout(300)
+
+    new_theme = user_page.evaluate(
+        "() => document.documentElement.getAttribute('data-theme')",
+    )
+    assert new_theme != initial_theme
+    assert new_theme in ("light", "dark")
+
+    stored = user_page.evaluate("() => localStorage.getItem('blog-theme')")
+    assert stored == new_theme
+
+    user_page.locator('[data-testid="theme-toggle"]').click()
+    user_page.wait_for_timeout(300)
+
+    restored_theme = user_page.evaluate(
+        "() => document.documentElement.getAttribute('data-theme')",
+    )
+    assert restored_theme == initial_theme
+
+    stored_restored = user_page.evaluate("() => localStorage.getItem('blog-theme')")
+    assert stored_restored == initial_theme