docs(protocol): close first v0.1 review

[FNB2026]

What changed

• record the 2026-07-26 Steward outcome for the first public v0.1 review
• accept RFC-0001 with individually attributable BlockDraft decisions and a minimum rejection record
• move RFC-0002 and RFC-0003 to Revision with explicit acceptance requirements
• update the protocol status, roadmap, and v0.1 changelog
• place the immutable tag and schema-digest manifest before OpenAPI and SDK publication

Why

The minimum seven-day review window has elapsed, but the RFCs still had unresolved questions and no recorded decision. This closes the review without treating private, uncommitted implementation experiments as public protocol contracts.

Public boundary

This PR changes public RFC/status documentation only. It does not copy authentication, worker, ledger, storage, IM/WebSocket, administration, deployment, private implementation code, or internal progress-analysis material into the public repository.

Validation

• git diff --check
• JSON parse checks for examples, schemas, and conformance fixtures
• tools/validate-public-artifacts.py
• tracked secret-bearing file and private-key checks
• verified fnb-progress-gap-analysis/ remains untracked

Validation result: validation passed: 10 schemas, 6 protocol-chain objects, full valid-instance coverage, negative fixtures