chore: remove moon new scaffold

[brickfrog]

Removes the moon new scaffold leftovers — the placeholder cmd/main package (a Hello-world main) and the stray top-level moon.pkg / pkg.generated.mbti.

These sit outside the src source root but were still being bundled into the published package (cmd/main/* and the root pkg.generated.mbti appear in the 0.8.0 zip). After removal the published artifact contains only src/, the manifest, and docs.

Verified: moon check / moon build / moon test (297 passed, all targets) / moon fmt --check clean; moon publish --dry-run packages only src/ + manifest + docs. No references to cmd/main in CI, docs, or hooks.

[brickfrog]

Choir: GitHub Actions rollup reports all checks successful on the latest head — re-check review/merge policy on GitHub (not an approval or merge signal by itself).

[Copilot]

Pull request overview

This PR removes leftover scaffolding produced by moon new (a placeholder cmd/main package plus stray top-level moon.pkg / pkg.generated.mbti) so they are no longer bundled into the published artifact, keeping the published package focused on src/ + manifest + docs.

Changes:

• Deleted the placeholder cmd/main package (including its moon.pkg and generated metadata).
• Removed stray top-level scaffold files (moon.pkg, pkg.generated.mbti) that were outside the src source root.
• Documented the removal in CHANGELOG.md under [Unreleased].

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg.generated.mbti	Removes stray generated package metadata from the repository root.
moon.pkg	Removes an empty stray top-level moon.pkg file.
cmd/main/pkg.generated.mbti	Removes generated metadata for the scaffolded cmd/main package.
cmd/main/moon.pkg	Removes the scaffolded cmd/main package manifest (including is-main).
cmd/main/main.mbt	Removes the Hello World scaffold main entry point.
CHANGELOG.md	Records the scaffold removal in the Unreleased changelog.

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[brickfrog]

Choir: GitHub Copilot issue-thread comment observed on PR — parent notified with updated gate snapshot (not merge approval).