Prepare providers release 2026-08-08

[potiuk]

Google-only wave, following the removal of google from the 2026-08-06 wave on
a binding -1 (the provider does not install on Python 3.14 — tracked in #71268,
worked around in #71273).

google 22.3.0 was cut as rc1/rc2/rc3 but never published, so its existing
changelog section is extended rather than superseded and the version stays
22.3.0 — it will be cut as 22.3.0rc4. source-date-epoch is unchanged for the
same reason.

Changelog entries added for the commits that landed after the 2026-08-06 cut:

• Workaround bug in google-claude-aiplatform evaluation extra (Python 3… #71273 → Misc (dependency change; the commit subject says
  "google-claude-aiplatform" and "Python 3.15", both of which are wrong, so the
  entry is reworded to what actually shipped)
• Prepare providers release 2026-08-01 #70932, Update changelog with better wording #71161, Prepare providers release 2026-08-06 #71219 → excluded block (release plumbing, plus a wording fix
  to a historic changelog note)

No inter-provider >= floor changed, so this does not need the
allow provider dependency bump label.

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Code (Opus 5)

Generated-by: Claude Code (Opus 5) following the guidelines