Remove automatic npm publication

[roackb2]

What changed

• remove the main-branch npm publication workflow for all five @heddleagent/* packages
• remove release-state selection, GitHub release finalizers, registry mutation modes, and their dedicated tests
• keep PR package checks, but make pack verification local-only and non-publishing
• replace the active release documentation with one explicit manual npm publication flow, including interactive OTP/browser approval

Why

npm publication still requires operator authentication, so merging to main must not pretend that publishing, tagging, or GitHub release creation completed automatically. This returns releases to a simple and truthful manual boundary.

Impact

Package contents, versions, exports, and normal build/test behavior are unchanged. Future releases require an explicit annotated tag, GitHub release, and manual npm publish command.

Validation

• yarn lint
• yarn test:unit (137 files, 904 tests)
• yarn package-family:verify
• node --check scripts/verify-execution-host-client-pack.mjs
• node --check scripts/verify-postgres-pack.mjs
• git diff --check