Meditation timer and shared video list

Two small shared features for namit and freya, both backed by Supabase instead of markdown since the data is append-only and multi-person.

Meditation

• Countdown timer with wake-lock (and a Safari no-sleep fallback)
• Weekly ledger of who meditated which day, plus a lifetime "cairn" of per-person stone counts
• Reused the same unlock-cookie gate as Challenges for writes
• Week navigation loads the full log history up front so browsing older weeks needs no extra fetch

Videos

• Grid of embedded, lazy-loaded YouTube iframes
• Add-URL bar accepts comma-separated links; each is validated before submit, and failed ones are left in the input so a retry only resubmits what didn't go through

Notes

The unlock-cookie pattern from Challenges turned out to be reusable as-is — worth keeping in mind for the next gated-write feature instead of inventing a new mechanism.