test: add unit tests for state and git lib modules

[TerminalGravity]

Adds 18 new unit tests covering two previously untested lib modules.

state.ts (10 tests): loadState, saveState, appendLog/readLog, now()
git.ts (8 tests): getBranch, getStatus, commits, staged files, error handling

Test count: 43 → 61. All green.

[TerminalGravity]

CI fails because the git lib test creates commits but the runner has no git identity. Need to add git config user.email and git config user.name in the test setup (beforeAll) for the temp repo. Test logic itself looks good — just this env issue.

[TerminalGravity]

CI is failing — the git tests need git config user.name and user.email set in CI. The runner doesn't have a global git identity configured, so git commit fails with fatal: empty ident name.

Fix: add a setup step in the test (or in CI) to configure a dummy git identity:

beforeAll(() => {
  execSync('git config user.name "Test" && git config user.email "test@test.com"', { cwd: tmpDir });
});

Or add it to the CI workflow before npm test. The other test PRs all pass — this is the only one affected.

[TerminalGravity]

Superseded by newer test PRs (#117, #102).