Extract rule: template-no-unbound

[NullVoxPopuli]

Split from #2371.

[NullVoxPopuli-ai-agent]

Review: template-no-unbound (comparing with ember-template-lint no-unbound)

Coverage

The migration looks clean and faithfully reproduces the original rule. The original checks MustacheStatement, BlockStatement, and SubExpression -- this PR correctly maps those to GlimmerMustacheStatement, GlimmerBlockStatement, and GlimmerSubExpression.

What's done well

• Correct node type mapping: All three visitor types from the original are covered.
• Error message: Closely matches the original ("Unexpected {{unbound}} usage." vs original "Unexpected {{unbound}} usage."). Essentially identical.
• Good test coverage: Both .gjs/.gts (via ember-eslint-parser) and .hbs (via ember-eslint-parser/hbs) are tested.
• templateMode: 'loose' is appropriate since unbound is a legacy helper that wouldn't appear in strict mode.
• Clean, minimal implementation -- easy to review and maintain.

Observations

• The original rule checks node.path.original === 'unbound' directly without the ?.type guard. The PR adds node.path?.type === 'GlimmerPathExpression' which is a reasonable defensive check for the ESLint AST. Good.
• The original test has 2 valid and 2 invalid cases. The PR has 3 valid (adds {{this.value}} for gjs) and 2 invalid per parser mode -- adequate coverage.

Verdict

This is a straightforward, correct migration. No issues found.

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🤖 Automated review comparing with ember-template-lint source