Phase 2: stand up @stackbilt/build package and release pipeline

[stackbilt-admin]

Phase 2 execution for Charter RFC #112: stand up @stackbilt/build in this repository.

Scope:

• Port CLI command surface from Charter: login, architect, scaffold, run
• Port supporting modules: credentials, http-client, scaffold contract types
• Port baseline tests: credentials/auth wiring/login warning coverage
• Set package metadata: @stackbilt/build with stackbilt bin
• Add CI + release workflow using npm trusted-publisher OIDC
• Publish initial npm version and validate install + stackbilt run path

References:

• Charter issue: phase 2: stand up @stackbilt/build in new Stackbilt-dev/stackbilt-build repo charter#125
• RFC umbrella: RFC: Extract commercial surface from @stackbilt/cli into @stackbilt/build charter#112