Source PQS dashboard version from Scribe annotation

[danielporterda]

Summary

• Resolve the version-dashboard PQS row from the public Scribe component image manifest instead of scanning participant-query-store image tags.
• Read org.opencontainers.image.version from europe-docker.pkg.dev/da-images/public/components/scribe:3.5 using the Docker/OCI registry API, so the workflow does not need an oras CLI dependency.
• Keep the previously published stable PQS dashboard value when the floating Scribe release-line tag resolves to a prerelease such as 3.5.3-rc2.
• Update focused generator tests for stable annotation updates, prerelease fallback, prior-stable selection, and rendered source metadata.

Validation

• direnv exec . python3 -m pytest tests/test_generate_network_component_versions.py -q
• direnv exec . python3 -m py_compile scripts/generate_network_component_versions.py tests/test_generate_network_component_versions.py
• SKIP_NPM_INSTALL=1 direnv exec . sh -lc 'python3 scripts/generate_network_component_versions.py --dry-run | jq ".repositories.pqs, ._generated.sourceContract.pqs"'
• git diff --check

The live dry-run currently keeps PQS at 3.5.2 because scribe:3.5 resolves to prerelease 3.5.3-rc2.