Sweep release.yml concurrency + checkout@v5 fix across all repos

[BryanFRD]

Context

After FerrLabs/.github#56 and FerrLabs/FerrFleet-Cloud#202, the release workflow template now has:

• concurrency: release-${{ github.ref }} with cancel-in-progress: false — prevents concurrent merges from racing and producing the E2006: tag already exists error.
• actions/checkout@v5 (instead of @v6 which drops GITHUB_TOKEN on deep fetch).

Existing repos that copied the template before the patch still have the old release.yml (or inline release job in ci.yml). Each needs the same two-line patch.

Repos to sweep

• FerrLabs/FerrFlow
• FerrLabs/FerrFlow-Cloud
• FerrLabs/FerrVault (operator — has release.yml)
• FerrLabs/FerrVault-Cloud
• FerrLabs/FerrTrack-Cloud
• FerrLabs/FerrGrowth-Cloud
• FerrLabs/FerrLens-Cloud
• FerrLabs/FerrGames-Cloud
• FerrLabs/FerrLabs-Cloud
• FerrLabs/UI
• FerrLabs/Kit
• FerrLabs/MCP
• FerrLabs/Benchmarks
• FerrLabs/Fixtures

Patch

# under the release job:
concurrency:
  group: release-${{ github.ref }}
  cancel-in-progress: false

# in the checkout step:
- uses: actions/checkout@v5  # was @v6

Can be done mechanically with a sed sweep + 1 PR per repo. Mergeable as chore(ci): (no semver bump).