docs: prepare final Sibyl submission pack

[moneyparking]

Decision

Prepare the remaining public-media and private-build-page gates against the current official Sibyl rules.

Changes

• add an explicit README "How memory made this possible" note
• explicitly declare that no optional Base or Virtuals stack is claimed
• require the cold-start recall beat to be one continuous, unedited segment
• require an on-screen commit hash and UTC timestamp before A/B/C
• add the two required public-post gates with @sibylcap
• add a truthful docs/SUBMISSION_DRAFT.md for the private Sibyl build page
• keep demo URL, build-page URL, post URLs, registration display name, PMF, and partner claims unresolved until verified

Official requirement source

• https://hack.sibyllabs.org/rules
• https://hack.sibyllabs.org/submissions

Verification

• exact branch head: ea2e1ff60afbc8c6aa3f9b663b74264bdb5a68bf
• branch CI: run 33536114826 — success
• runtime files unchanged from deletion/license merge cbb2422

Remaining owner-only gates

• provide the private registration build-page URL
• record and upload the 2–5 minute video
• verify the public video anonymously
• publish demo and build-log posts
• fill, mark ready, and read back the private build page