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/TEST_MODEL.md

@@ -17,10 +17,10 @@ adding new tests.
 | Keycloak Auth Client | 80% | — | — | — | P0 | ✅ Active |
 | App Bootstrap & Config | 75% | — | — | — | P1 | ✅ Stable |
 | Transaction Manager | 60% | — | — | — | P2 | ⚠️ Partial |
-| Web UI Error Handling | — | — | — | 40% | P1 | ⚠️ Partial |
-| Pagination | 40% | — | — | — | P1 | ⚠️ Partial |
-| Post Edit via Web | — | — | — | — | P1 | ❌ Missing |
-| Post Delete via Web | — | — | — | — | P1 | ❌ Missing |
+| Web UI Error Handling | — | — | — | 50% | P1 | ⚠️ Partial |
+| Pagination | 40% | — | — | 60% | P1 | ⚠️ Partial |
+| Post Edit via Web | — | — | — | 40% | P1 | ⚠️ Partial |
+| Post Delete via Web | — | — | — | 40% | P1 | ⚠️ Partial |
 
 Legend: ✅ Covered / ⚠️ Partial / ❌ Missing / — Not Applicable