feat: prove physical Sibyl deletion

[moneyparking]

Decision

Close the two highest-priority competition gates without weakening the authority boundary:

1. prove physical Sibyl authority-row deletion through the official SDK;
2. replace the incomplete license stub with the full standard MIT License.

Runtime change

• add SibylAuthorityMemoryStore.delete_authority_events(entity_id)
• delete only rows whose structured body matches the exact entity
• call official MemoryClient.delete_entity(category, name)
• add a three-process physical-deletion acceptance:
  • A: write and authorize the human grant
  • B: hard-delete one exact-entity row
  • C: reopen the same database, read zero rows, require new human authority
• preserve the separate memory-unavailable fail-closed acceptance

TDD evidence

• adapter RED: commit 6064a6e, run 33534656483 — expected missing-method failure
• adapter GREEN: commit 8275660, run 33534738164 — success
• CLI RED: commit f2a7f33, run 33534833256 — expected missing-script failure
• final exact-head branch CI: run 33535377602 — success

Exact-head evidence

• sibyl-memory-client==0.8.0
• 13 passed in 0.88s
• recall/revocation: AUTHORIZED → AUTHORIZED → INVALIDATED
• physical deletion: deleted_rows=1 → remaining_rows=0 → HUMAN_REQUIRED
• post-delete governed action: false
• memory unavailable: BLOCKED / AUTHORITY_MEMORY_UNAVAILABLE / false

Trust boundary

This proves application-level SQLite row hard deletion through Sibyl's official API. It does not claim forensic secure erasure of SQLite page remnants, the database file, or the storage medium.

Documentation and compliance

README, Judge Guide, Acceptance Evidence, Demo Script, and Build Status now describe the same implemented system. LICENSE contains the complete standard MIT text.