chore: refresh generated beta spec

[github-actions]

Automated regeneration of beta/openapi.beta.yaml (the embedded dci beta
command surface) detected drift against the source spec. Review the shape
changes below; merging updates what the next release embeds.

If an operation listed in beta/manifest.yaml disappeared from the source
spec, the generator fails instead of opening this PR — that case needs a
manifest edit (likely a GA promotion; see BETA-SPEC.md §2.8).

[claude]

LGTM, straightforward generated-spec refresh. Reviewed: the single changed file is the auto-generated beta/openapi.beta.yaml (header/sha256 bump consistent with "DO NOT EDIT, regenerate via tools/betaspec"); confirmed beta/manifest.yaml is unchanged, which matches the diff only touching field-level details within already-curated operations (no additions/removals requiring manifest edits); checked Go source and command-docs for references to the renamed/removed fields (createdAt, csv_export/sheets_export, not_between, ExampleAttribution10/20) — none found, so nothing hardcodes the old shapes; the new example IDs (RB8DndcxODriK83IBXXf, D7r4znsTj2UC95zGnunW) read as synthetic placeholders, not captured real identifiers.

Extended reasoning...

Single-file diff to the generated beta/openapi.beta.yaml (sha256 bump, new fileOutput query param, field renames/removals, enum code changes, doc text), authored by the github-actions bot per the repo's regeneration workflow; no auth/crypto/permission logic touched, and no manifest or Go source changes needed since it's purely spec-field churn. Verified no Go code or command-docs reference the old field names/enum values being removed, and beta/manifest.yaml is untouched, which is consistent with the PR's own description of the generator's failure mode. Decided approve given the change is mechanical, self-contained to a generated artifact, matches its own description, and carries no outstanding review objections in the timeline.