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_pagination.py

@@ -0,0 +1,111 @@
+"""End-to-end tests for pagination on the home and posts listing pages.
+
+Tests that pagination controls appear when there are more posts than the
+page size, that navigation between pages works, and that boundary controls
+are correctly disabled on the first and last pages.
+"""
+
+from __future__ import annotations
+
+import pytest
+from playwright.sync_api import Page
+
+from tests.e2e.pages import HomePage
+
+
+def _seed_posts(page: Page, base_url: str, count: int) -> None:
+    """Create published posts via form POST to ensure pagination exists.
+
+    Args:
+        page: Authenticated Playwright page.
+        base_url: Application base URL.
+        count: Number of posts to create.
+    """
+    for idx in range(count):
+        response = page.request.post(
+            f"{base_url}/web/posts/new",
+            form={
+                "title": f"Pagination Seed {idx:03d}",
+                "content": f"Content for seed post {idx}.",
+                "tags": "pagination",
+                "action": "publish",
+            },
+        )
+        assert response.ok, f"Failed to create post {idx}: {response.status}"
+
+
+@pytest.mark.e2e
+def test_pagination_navigation_across_pages(
+    user_page: Page,
+    base_url: str,
+) -> None:
+    """Test pagination navigation between pages.
+
+    Steps:
+        1. Ensure enough posts exist for pagination.
+        2. Open home page and verify page 1 boundary state.
+        3. Click "Next" and verify page advances.
+        4. Click "Previous" and verify back on page 1.
+
+    Args:
+        user_page: Playwright page authenticated as regular user.
+        base_url: Application base URL.
+    """
+    home = HomePage(user_page, base_url)
+    home.open()
+
+    if not home.can_go_next():
+        _seed_posts(user_page, base_url, 12)
+        home.open()
+
+    assert home.get_current_page() == 1
+    assert not home.can_go_prev()
+    assert home.can_go_next()
+    assert home.count_posts() <= 10
+
+    with user_page.expect_navigation(wait_until="networkidle"):
+        home.go_to_next_page()
+
+    assert home.get_current_page() == 2
+    assert home.can_go_prev()
+    assert home.count_posts() <= 10
+
+    with user_page.expect_navigation(wait_until="networkidle"):
+        home.go_to_prev_page()
+
+    assert home.get_current_page() == 1
+    assert not home.can_go_prev()
+
+
+@pytest.mark.e2e
+def test_pagination_boundary_on_last_page(
+    user_page: Page,
+    base_url: str,
+) -> None:
+    """Test that the last page has "Next" disabled and "Previous" enabled.
+
+    Steps:
+        1. Ensure enough posts exist for pagination.
+        2. Navigate through all pages to the last one.
+        3. Verify boundary controls on the last page.
+
+    Args:
+        user_page: Playwright page authenticated as regular user.
+        base_url: Application base URL.
+    """
+    home = HomePage(user_page, base_url)
+    home.open()
+
+    if not home.can_go_next():
+        _seed_posts(user_page, base_url, 12)
+        home.open()
+
+    assert home.can_go_next()
+
+    while home.can_go_next():
+        with user_page.expect_navigation(wait_until="networkidle"):
+            home.go_to_next_page()
+
+    assert home.can_go_prev()
+    assert not home.can_go_next()
+    assert home.count_posts() <= 10