release: prepare v0.6.0 with required CI evidence

[brainx]

Prepare Zeus 0.6.0 with readiness schema 9 and require successful CI from the latest main-branch push of the exact tagged commit before release artifacts are built or uploaded. The gate checks every integration job, rejects incomplete or stale rerun evidence, and preserves the existing verified tag and commit requirements.

Both release verifiers close HTTP error responses before reporting a redacted failure. Regressions cover redirect, authentication, rate-limit and server errors, including cleanup failures and Python 3.14 resource warnings.

Update package/OpenAPI versions, release notes, upgrade guidance and the roadmap for the implemented Hermes diagnostics and operator messaging work. This PR follows #43 and must land after #23, #41, #42 and #43.

Validation:

• make release-check on 946ce66: 1,556 tests passed in both runs, three expected skips, 83.91% coverage; static checks, wheel/source builds, installed-wheel smoke, Twine and checksums passed.
• The subsequent HTTP cleanup fix passed 28 focused tests on both Python 3.13.15 and 3.14.7 with zero ResourceWarnings; formatting, Ruff and mypy passed.
• GitHub CI on 2d70de386548a0bba9c3852b840423173a48d8c1: all 18 push/PR checks passed. Python 3.13 ran 1,558 tests twice with two expected platform skips and 83.75% coverage.
• The release checker accepted the current main commit's actual GitHub CI metadata through its default HTTPS transport; the new tagged release workflow has not run yet.
• Olymp exercised real installed-wheel APIs for Zeus 0.5.0/schema 6, 0.6.0.dev0/schema 9 and 0.6.0/schema 9, including authentication, approval, reconciliation replay and version/schema rejection.
• The candidate artifact passed archive and distribution checksum checks; all 121 packaged files and 202 source-archive tracked files match the commit.

Release promotion remains pending the required human review, integration of this stack, CI on the resulting main commit and a GitHub-verified signed release tag. Upgrading persistent state to schema 9 requires a pre-upgrade backup for rollback; databases are not downgraded.