Correct adopter-facing examples and wire-version docs

[jasonodoom]

A few example patterns would be rejected by a conforming receiver, and the wire-version note read as broader than it is.

• foreign-sender-receiver signed the transport auth over a fresh timestamp instead of the envelope's own, so the receiver cannot reconstruct the signature base. It now uses the envelope timestamp, matching reference-sender.
• interop-cli parsed the response Authorization header loosely (accepting trailing data and a second parameter) and validated discovery cards too leniently. Both are tightened to the anchored grammar and the required card members, including a top-level publicKeyMultibase.
• interop-cli build without a seed produced an envelope whose from did not encode the signing key. It now derives or checks the did:key.
• README and the maturity notice now state ink/0.2 versions only the intent-envelope body-signature domain; the card, handshake, receipt and audit objects stay ink/0.1.

Examples and docs only; no library or conformance change.