chore(release): v9.1.0 [skip-runtime-e2e]

[saurabhjain1592]

Release v9.1.0

This is a version-bump + CHANGELOG release PR only. No code changes here - the entire 9.1.0 payload is already merged to main across the #3254 pin-advance batch and the caller_name work:

• Additive audit read-model wire fields. policy_decision, policy_details, response_time_ms on the audit read model, and action on audit search. request_type is deprecated (never read on the 9.x line). All additive and absence-tolerant.
• masfeat/OJK model extension (#3254 pin-advance batch). Real wire fields added; the never-served fiction fields deprecated. No field removed.
• OpenAPI spec pin advanced to community v9.13.0.

No field or public API name was removed, so this is a proper MINOR (fields added, some deprecated). Platform v9.14.0 is released and /health advertises SDK 9.1.0, so this must ship.

The CHANGELOG [Unreleased] section was moved wholesale under a new ## [9.1.0] - 2026-08-04 header, leaving a fresh empty [Unreleased] above it. The version-alignment gate and the release preflight both pass locally against 9.1.0.

Version files bumped

• pyproject.toml -> version = "9.1.0"
• axonflow/_version.py -> __version__ = "9.1.0"

Verification

• Version imports as 9.1.0 (pyproject + _version.py)
• validate-version-alignment.sh passes

After merge (master runs the tag; this triggers the PyPI publish)

git tag v9.1.0 <merge-commit> && git push origin v9.1.0

Skip-runtime-e2e justification

This is a mechanical release version bump: it changes only the version file(s) and the CHANGELOG (retitling the Unreleased section to [9.1.0]). No runtime surface changes. The code shipped in 9.1.0 (the additive audit read-model wire fields, the masfeat/OJK model extension, and the OpenAPI spec pin) landed in prior PRs that each exercised the runtime-e2e suite; a version stamp has no new user-facing behavior to demonstrate. Skip applied under the v9.14.0 release-train execution.