Moves the moderation warning badge ("Content blocked...") to overlay the blurred thumbnail image instead of sitting below it or increasing card height. This logic is applied to both the main `VideoCard` and the `SimilarContentCard` to ensure layout consistency.
Changes:
- VideoCard.js: Refactor `updateModerationBadge` to append the badge container as a child of the `anchorEl` (thumbnail wrapper) with absolute positioning.
- SimilarContentCard.js: Implement `refreshModerationUi` logic to generate and overlay a simplified moderation badge on the thumbnail when `trustedMuted` context is present.
- Fix tests/moderation/video-card.test.mjs: Patch test environment to mock `globalThis.navigator`.