test: enforce 100 percent coverage for core TypeScript modules

Summary

This MR enforces 100% automated coverage for the repo's core executable TypeScript modules and fills the existing test gaps.

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What Changed

• Added explicit Vitest coverage configuration in vite.config.ts
• Enforced 100% statements, branches, functions, and lines
• Scoped enforced coverage to:
  • src/modules/**/*.ts
  • src/services/**/*.ts
  • src/store/**/*.ts
  • src/utils/**/*.ts
• Excluded barrel index.ts files from enforced coverage
• Expanded tests for:
  • Corpus service parsing and fetch/runtime edge cases
  • Team seed CSV parsing and preload-building edge cases
  • Standup verification date and alias handling
  • Barrel export consistency
• Fixed production edge cases surfaced by the new tests
• Updated contributor docs and changelog
• Updated tsconfig.node.json so config type-check remains green with the Vitest config import

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Validation

npm run validate
npm run test:coverage

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Result

• npm run validate passed
• npm run test:coverage passed
• 54 tests passed

Coverage

• 100% statements
• 100% branches
• 100% functions
• 100% lines

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Notes

Coverage enforcement applies to the repo's core logic modules. This MR does not attempt full UI/component coverage.