fix: correct support for workspace:^ and backstage:^ dependency version resolution.

[davidfestal]

Fix workspace:^ and backstage:^ dependency version resolution

Summary

Fixes how the dynamic plugin export resolves workspace:^ and backstage:^ version specs in plugin dependencies, which previously produced incorrect or unresolvable versions in the exported package.json.

Changes

• New backstageVersion module (src/lib/backstageVersion.ts): Adds utilities to resolve backstage:^ version specs to concrete versions by fetching the Backstage release manifest (via @backstage/release-manifests). Replicates the logic from the Backstage Yarn plugin's beforeWorkspacePacking hook. Supports BACKSTAGE_MANIFEST_FILE and BACKSTAGE_VERSIONS_BASE_URL environment variables for offline / custom manifest usage.

• Fix workspace:^ range specifier handling (backend.ts): The ^ / ~ range prefix was incorrectly applied inside the monorepo-package resolution branch, meaning it was lost in certain code paths. Moves the range-prefix prepending to run after all resolution branches so it is applied consistently.

• Add backstage:^ protocol support (backend.ts): When a dependency uses the backstage:^ protocol, it is now resolved to a concrete ^<version> using the release manifest, with a log message showing the resolution.

• Add @backstage/release-manifests as a production dependency.

• Minor: simplify the bin field in package.json to a plain string.

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[PatAKnight]

lgtm