Feat/unittest

MR Title test: add vitest-based unit test coverage for core logic

Description

• Replaced ad-hoc test execution with Vitest.
• Added npm scripts: test, test:watch, test:coverage.
• Added coverage tooling and ignored generated coverage/ artifacts.
• Added unit tests for:
• CSV parsing (parseInternsCSV, parseTeamSeedCSV, buildPreloadedTeams)
• Corpus API service behavior (corpusService)
• Team state and operations (teamStore, teamManager)
• Standup verification logic (verifyStandup)
• Kept build compatibility (npm run build passes).

Why

• Increases confidence in core business logic.
• Standardizes test execution for local dev and CI.
• Makes regressions easier to catch before deployment.

Validation

• npm test passes.
• npm run test:coverage passes.
• npm run build passes.
• Current suite: 32 tests across 6 test files.

Commits Included

• 7d8c3d1 test: migrate to vitest runner and coverage scripts
• 4ef50f2 test: add unit coverage for CSV parsing and corpus service
• bdf6b94 test: add team manager/store and standup verification tests