Add explicit first-contact requests and finite approval authority

[qh-work]

An independently created sender can discover an opted-in recipient and submit a fixed first-contact request without a pre-shared delivery grant. The recipient explicitly approves or rejects it; approval binds the original request, both parties, the node/epoch and a real finite delivery reservation. Python and native TypeScript use real dual-key possession challenges and durable request/result/replay capacity in the existing protected transport database.

This also fixes CONTACT-01: after a policy update, retained requests from the old policy no longer hide valid current requests. Both runtimes validate within the original transaction before applying the four-item / 16 KiB output limit, scan at most the existing 32 retained rows, and preserve old evidence, charges and authorization rejection.

Validated candidate: 5c43e3c02ad61965d46ea7572d28cd56af75656c.

• Exact-source open CI: 173 distinct methods passed, including the 74 first-contact methods and nine new CONTACT-01 regressions; 471 subtest events are separate. All 40 recorded source fingerprints match the candidate. The scale job was conditionally skipped.
• Three-platform core CI: the same eight methods passed on each platform. Its actual PR merge checkout has the same Git tree as the candidate.
• Actual 6 Pro review closed CONTACT-01 and returned PASS for code, packaging and exact-SHA CI evidence, with zero remaining blockers in this scope. Its own formal run was 18 pass, five dependency errors and four unexecuted methods; seven additional state-component checks passed separately. Review-side JOSE/TypeScript integration was unavailable, so cloud results remain separately attributed.
• The eight rebuilt candidate assets passed source/manifest checks and a bounded final-archive privacy review. The actual client ZIP passed its save/recall/Experience/hooks/backup-restore smoke check. Previous failed runs and the rejected parent candidate retain their original attribution.

Open send / receive remain unsupported. This preview provides first contact, explicit decisions and finite authority; encrypted delivery, both receipt types, cold mailbox discovery, offline repair and broader global acceptance continue in subsequent development. Requests and grants do not create Memory, author trust, execution rights or reverse-chat authority.