Fix release workspace version bump

[R-M-Naveen]

Summary

• replace workspace npm version calls in the release workflow with npm pkg set version
• avoids implicit workspace-local installs that can create nested packages/*/node_modules
• keeps the final npm install so the lockfile is regenerated after versions and internal dependency ranges are updated

Why

The v0.11.9 release rerun checked out main but failed tests because release-time workspace versioning created nested package installs that shadowed local workspaces with already-published @atxp packages. That made tests import stale 0.11.8 code during the 0.11.9 release.

Validation

• Simulated the release version-bump step in /tmp using npm pkg set version=0.11.9 and confirmed @atxp/client resolves @atxp/common@0.11.9 to the local workspace
• npx -y -p node@22 -p npm@10 npm run build in the simulated release worktree
• npx -y -p node@22 -p npm@10 npm test -w packages/atxp-client
• npx -y -p node@22 -p npm@10 npm test -w packages/atxp-express
• npx -y -p node@22 -p npm@10 npm test -w packages/atxp-server