Specify session profiles and allocate 0xF0A3

[germ-mark]

Specifies session profiles.

• Correct is the behavior the book specifies.
• Deployed-compatible adds the announced id in an id-changing A.5 Upd' and a reciprocal A.5 deferred until the peer's own A.5 lands. It is the frozen default.

Group rule 9 allocates CorrectProfile (0xF0A3):

• A classical key package's leaf advertises it in its capabilities, and a session runs the correct profile only when both parties' classical key packages do.
• The choice is recorded once, as an empty GroupContext extension of that type on the initiator's classical half. The acceptor checks it and mirrors it onto its return group. It is immutable under the GCE ban.
• A later wire-visible change ships as a new profile type.

Also:

• anomaly 5's resolution and the header-encryption AD row are scoped to deployed-compatible;
• passages that said an Upd' "announces" our identity now say its new leaf carries it;
• the trigger rule gains the own-catch-up gate (open it only once the peer has folded our new id);
• wire-format gets a codepoint table;
• stray text is removed from the group rules.

We confirmed that the deployed engine accepts a key package listing 0xF0A3. It rejects a group that records one, which rule 9 never does unless both key packages advertise it.

Book-only, with an empty changeset.

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