branch 4.1.0 and start 4.2.0

[bbrks]

CBG-5471

Integration Tests

• n/a

[github-actions]

Redocly previews

• Admin API
• Public API
• Metric API
• Diagnostic API

[Copilot]

Pull request overview

This PR performs the release-branch cutover for Sync Gateway 4.1.0 by adding a dedicated 4.1 manifest and updating the mainline/default manifests and version identifiers to begin 4.2.0 development.

Changes:

• Add manifest/4.1.xml pointing sync_gateway to release/4.1.0, and register it in manifest/product-config.json.
• Bump the default manifest and product API minor version from 4.1 → 4.2.
• Update OpenAPI info.version fields across the published API specs from 4.1 → 4.2.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
manifest/product-config.json	Registers the new 4.1 manifest entry and updates the default manifest release to 4.2.0.
manifest/default.xml	Updates build VERSION annotation to 4.2.0 for the mainline manifest.
manifest/4.1.xml	New manifest targeting the release/4.1.0 branch for the 4.1 line.
docs/api/public.yaml	Bumps OpenAPI info.version to 4.2.
docs/api/metric.yaml	Bumps OpenAPI info.version to 4.2.
docs/api/metric-capella.yaml	Bumps OpenAPI info.version to 4.2.
docs/api/diagnostic.yaml	Bumps OpenAPI info.version to 4.2.
docs/api/admin.yaml	Bumps OpenAPI info.version to 4.2.
docs/api/admin-capella.yaml	Bumps OpenAPI info.version to 4.2.
base/version.go	Updates ProductAPIVersionMinor to reflect API version 4.2.