[DO NOT MERGE] Validate workspace checksum publication

[Divyansh-db]

What changes are proposed in this pull request?

DO NOT MERGE — diagnostic sync validation, not a release. This PR shows the actual published-tree output of regenerating workspace checksums during synchronization, with a pre-fix control to isolate its effect.

The source snapshot predates the latest public release, #85, so the full diff against main also contains unrelated release and generated-code drift. The two commits separate these effects:

1. Pre-fix sync control: 269 files already differ without the checksum fix. These include older development-release changelogs and version constants, module requirement rollbacks (including zero-version options requirements in domains and sandbox), and five generated source files. The generated API drift includes removal of newer AI Gateway secret/service-credential variants.
2. Checksum-only change: only go.work.sum changes, from 61 to 25 lines. It remains committed in the public repository. SDK source, public APIs, module manifests, module sums, workspace configuration, and ignore rules are identical to the pre-fix control.

The checksum fix regenerates workspace sums against the public checkout's module sums instead of copying checksum state from a different workspace. The overall PR is not API-identical to current main, because it includes the first commit's pre-existing sync drift. No release preparation or version bump was run. Committed files retain the regular-file modes used by the publisher.

How is this tested?

• Ran the full synchronization against a fresh clone of public main, both with and without the fix, using the same generated API input and Go toolchain. Comparing the two outputs identified only go.work.sum as different.
• Ran Go tests across all 92 workspace modules with the examples build tag, race detector, and readonly module manifests; all passed. Tests ran in a separate copy to preserve the exact sync output in this PR.
• Sync regression and vendor-consistency tests passed.
• Go formatting and git diff --check passed.

These checks isolate the checksum fix's effect; they do not make the unrelated baseline rollbacks safe to merge.