chore(screenshots): add /notifications page proofshots for #153

18 screenshots: empty state, list view (~20 items), load-more view (~40 items)
across 320/768/1440 px viewports in light and dark themes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

proofshot-artifacts/2026-03-29_notifications-page-153/metadata.json

@@ -0,0 +1,6 @@
+{
+  "branch": "feature/153-notification-history",
+  "commitSha": "edeff353931e9d625083eec983fe174c138c340d",
+  "startedAt": "2026-03-29T00:00:00.000Z",
+  "description": "Notification history page (/notifications): empty state, list view (20 items), load-more view (40 items) — 320/768/1440px, light/dark"
+}