Native Media Spaces (Newsletters, Studio, Social & Photos), Save for Later & Story Dedupe

• 🔖 Save for Later Next to Share (s): Added a private 'Save' bookmark button right next to Share on every article card and in the slide-over reader, a dedicated 'Saved' stream in the sidebar and mobile quick chips, keyboard shortcut 's' (with Shift+S preserved for quick share), and automatic retention protection during database compaction.
• 🔗 Story Deduplication: Automatically folds duplicate story coverage across feeds sharing the same canonical outbound link or headline into an expandable '+N more feeds' cluster pill with 1-click 'Mark all read' and a toolbar 'Dedupe' toggle.
• ⚡ High Velocity & 💤 Inactive Subscription Health Filters: Added 'High Velocity' (>=5 items/day), 'Inactive' (no posts in 60+ days), and 'Broken' filter pills and per-feed velocity badges in Manage Subscriptions & Folders.
• ✉️ Native Newsletters Space: Dedicated Newsletters stream featuring your personal @webnerd.ai intake address banner at the top with 1-click Copy Email, inline issue delivery drawer, sender channel pills, and reading-time badges.
• ▶️ Native Video & Podcast Studio: Dedicated exclusively to subscribed YouTube channels and podcasts (excluding regular blog posts with embedded media), featuring a Google-authenticated YouTube Subscriptions Synchronizer ('Sync YouTube Subscriptions'), an in-Studio Channel & Podcast Search bar with 1-click subscribe, and a 3-wide playable 16:9 horizontal thumbnail grid where both YouTube videos and podcast episodes play directly inside the thumbnail tile.
• 📸 Native Social & Photos Space: Visual gallery and social pulse stream for photography feeds, art blogs, Reddit communities, and Bluesky / Mastodon feeds with multi-image mosaics and a full-screen Photo Lightbox viewer.
• 🛡️ Modern Web Standards & Security Hardening: Added Cross-Origin Isolation headers (COOP/CORP), Fetch Metadata API guards, __Host- session cookies, Clear-Site-Data logout & 1-click account deletion, and Trusted Types HTML sanitization.