Document intentional upstream renames & join-session return-shape divergence

[krukow]

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Document intentional upstream renames & join-session return-shape divergence

Found during the GA upstream parity audit (Phase 1). These are intentional Clojure-idiomatic
choices that are currently undocumented, which makes them read as parity gaps. Document them
(API.md + CHANGELOG) so the divergence is explicit and deliberate.

F5 — option/field renames vs upstream

• :disable-resume? — Clojure name for upstream suppressResumeEvent.
• :max-input-tokens — Clojure name for upstream maxPromptTokens (BYOK provider config).

Both are deliberate idiomatic renames. Add a short "naming differences vs the official SDK"
note in doc/reference/API.md mapping each Clojure key to its upstream counterpart.

F6 — join-session return shape

The Clojure join-session return shape diverges from the upstream equivalent. Document the
exact returned shape and call out the difference so callers porting from Node.js know what to
expect.

Scope

Documentation-only; no code change. To be handled in the Phase 4 documentation pass.

Severity: ga-nice-to-have, documentation.