build(sdk): publish @punktfunk/host to the Gitea npm registry

- package.json: drop private; point main/types/exports/bin at a tsc-built dist/;
  add publishConfig (unom/npm registry), files, repo metadata, and the
  MIT OR Apache-2.0 license; effect becomes a peerDependency (shared instance).
- tsconfig.build.json: emit dist/ JS + .d.ts (bun shebang preserved on the bin).
- .npmrc: map the @punktfunk scope to the registry (no token committed).
- sdk-publish.yml: publish on sdk-v* tags or manual dispatch, reusing the
  REGISTRY_TOKEN secret; typecheck/test/build/tag-matches-version gate.
- README: Install section for consumers.

Verified: build green, frozen lockfile stable, bun publish --dry-run packs
@punktfunk/host@0.1.0 (dist + README only) to the unom registry.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

sdk/.npmrc

@@ -0,0 +1 @@
+@punktfunk:registry=https://git.unom.io/api/packages/unom/npm/