Show extension checksums in CLI output

[IlyaasK]

Summary

• show extension checksums in human-readable list output
• show the full checksum after extension get and upload operations
• document checksum metadata in the CLI command reference

Why

Kernel now exposes the checksum of the exact uploaded extension archive. Showing it in the CLI lets operators identify and verify durable extension artifacts without dropping to a raw API request.

Implementation

List output adds a compact checksum column. Get and upload output print the checksum outside the width-bounded table so the complete digest remains available in normal terminal output. Legacy extensions without a checksum render -; JSON output remains the unmodified SDK response.

Verification

• go test -short -timeout=2m ./...
• go vet ./...
• gofmt -l cmd
• git diff --check
• targeted mutation checks for list, get, and upload checksum output: 3/3 killed
• crap4go: changed functions remain below the repository's existing CRAP hotspots

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Note

Low Risk
CLI presentation and docs only; no changes to upload logic, auth, or API behavior beyond displaying an existing SDK field.

Overview
Surfaces Kernel’s extension archive checksum in the CLI so operators can verify durable artifacts without raw API calls.

kernel extensions list adds a Checksum column (missing values show - via util.FirstOrDash). get and upload print the full digest on its own line after the property table so long hashes aren’t clipped. README documents checksum in extensions get metadata. --output json is unchanged (SDK response only). Tests cover list/get/upload checksum output.

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