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

app/presentation/web/routes.py

@@ -144,7 +144,7 @@ async def _get_visible_posts(
         own_drafts = [p for p in own if p.id not in published_ids and not p.published]
         merged = list(published) + own_drafts
         merged.sort(key=lambda p: p.created_at, reverse=True)
-        return merged[:limit], has_next or len(own_drafts) > 0
+        return merged[:limit], has_next
 
     return published, has_next