What

Adds 5 unit tests for the empty-block lint pass in packages/language/src/lint/empty-block.ts. Brings the rule's test count from 0 to 5.

Why

The empty-block rule flags empty inputs: and outputs: blocks (a common authoring mistake) but had no tests pinning down its behavior. This change closes the gap using the same pattern PR #38 (required-fields.test.ts) established for lint-rule tests.

How

New test file at packages/language/src/lint/empty-block.test.ts using vitest. Follows required-fields.test.ts exactly: single describe block, flat it cases, shared getDiagnostics helper, ActionsBlock-based test schema.

The 5 cases:

1. Flags a bare inputs: with no entries
2. Does not flag a populated inputs: block
3. Flags a bare outputs: with no entries
4. Reports two diagnostics when both inputs: and outputs: are empty
5. Reports one diagnostic per action when multiple actions have empty blocks

Test Plan

pnpm --filter @agentscript/language test empty-block

Result:

✓ src/lint/empty-block.test.ts (5 tests) 11ms
Test Files  1 passed (1)
     Tests  5 passed (5)

• pnpm --filter @agentscript/language test empty-block — 5/5 passing
• npx eslint --config eslint.config.js packages/language/src/lint/empty-block.test.ts — exit 0
• New/updated tests cover the change — N/A (this PR is the tests)

Checklist

• My code follows the project's coding style
• I have reviewed my own diff
• I have added/updated documentation as needed
• This change does not introduce new warnings