feat(selfdev): expose upgrade-safe build identity

[yansigit]

Summary

Expose durable build identity and upgrade-channel information so self-dev client and shared-server binaries can be diagnosed and safely rolled back after upgrades.

Changes

• Report source revision, build channel, and protocol identity.
• Document immutable binary channels and promotion/rollback behavior.
• Preserve user state and provider compatibility across application updates.

The external provider protocol and extension registry are separate concerns and are not part of this PR's intended review scope.

Validation

• Rebasing onto current upstream/master completed successfully.
• Focused build-support and protocol tests passed.
• The full jcode test suite has one unrelated auth lifecycle failure in the current baseline.

Closes #1257
Refs #917
Refs #799

[greptile-apps]

Confidence Score: 5/5

The outstanding recovery concern is non-blocking; no blocking issues were identified.

Findings

1.  Rollback guarantee has gap ▶

Fix with agent prompt

### Issue 1
docs/SELFDEV_UPGRADE.md:30-33
The guide promises that a failed reload records pending activation and restores both channels, but publication moves `current` before `PendingActivation` is durably saved. If the process stops in that interval, the new `current` remains active without the previous channel pair required for automatic rollback. This is a non-blocking documentation and recovery concern; either make publication and activation recording recoverable as one operation or document this interruption case.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

Exposes build identity through the version command and documents the self-development upgrade workflow.

• Adds runtime-derived selfdev, release, and development build channels.
• Reports the external-provider protocol version in plain-text and JSON version output.
• Documents immutable binary channels, state preservation, promotion, and rollback expectations.
• Updates CLI test fixtures for the extended version and model-route structures.

_{Reviews (2) · Last reviewed commit: "style(selfdev): normalize upgrade guide"}

[greptile-apps]

Rollback guarantee has gap

The guide promises that a failed reload records pending activation and restores both channels, but publication moves current before PendingActivation is durably saved. If the process stops in that interval, the new current remains active without the previous channel pair required for automatic rollback. This is a non-blocking documentation and recovery concern; either make publication and activation recording recoverable as one operation or document this interruption case.

Prompt To Fix With AI

This is a comment left during a code review.
Path: docs/SELFDEV_UPGRADE.md
Line: 30-33

Comment:
**Rollback guarantee has gap**

The guide promises that a failed reload records pending activation and restores both channels, but publication moves `current` before `PendingActivation` is durably saved. If the process stops in that interval, the new `current` remains active without the previous channel pair required for automatic rollback. This is a non-blocking documentation and recovery concern; either make publication and activation recording recoverable as one operation or document this interruption case.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.