docs(release): read catalog schema version from any runtime file

[samzong]

What's changed?

• The release skill reads CatalogSchemaVersion from pkg/runtime/*.go instead of pkg/runtime/catalog.go.

Why

• The constant lives in pkg/runtime/catalog_schema.go. Reading catalog.go yields an empty value, so every jq --argjson schema "$CATALOG_SCHEMA" check in the release gate fails with "invalid JSON text passed to --argjson".

Verification

• Old command prints an empty value; new command prints 29, matching pkg/runtime/catalog_schema.go:3.
• The v0.6.3 release gate ran with the corrected path and all generated CLI catalog checks passed.
• make check passes.

[codspeed]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 21 untouched benchmarks

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_{Comparing docs/release-catalog-schema-source (4aeac4f) with main (68b28df)}