feat(ci): add vitest code coverage analysis

[quanticsoul4772]

Summary

Resolves #20.

• Add vitest.config.ts at root with @vitest/coverage-v8 provider, text/lcov/html reporters, workspace package aliases, and minimum thresholds (60% lines/functions/statements, 50% branches)
• Add @vitest/coverage-v8 to root devDependencies
• Add test:coverage script (vitest run --coverage)
• Update test.yml GitHub Actions workflow: run test:coverage after test, upload coverage/ as a 30-day artifact

Test plan

• pnpm run test:coverage runs without error and emits coverage summary
• coverage/ directory created with index.html and lcov.info
• GitHub Actions Coverage step uploads the artifact on PRs to main
• Coverage thresholds fail the build if they drop below 60%/50%

🤖 Generated with Claude Code

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[priyanshus]

@quanticsoul4772 Thanks for the PR. Can you please check why tests are failing.

[quanticsoul4772]

Tests aren't actually running, CI fails at the install step:
Code
The PR added @vitest/coverage-v8 to devDependencies but the lockfile wasn't regenerated. Fix is one commit: pnpm install locally, then commit the updated pnpm-lock.yaml. Pushing that now.

[quanticsoul4772]

@priyanshus The failing check was the install step, not the tests — CI rejected pnpm install --frozen-lockfile because the lockfile didn't include the new @vitest/coverage-v8 specifier:

ERR_PNPM_OUTDATED_LOCKFILE  Cannot install with "frozen-lockfile"
because pnpm-lock.yaml is not up to date with <ROOT>/package.json

Pushed 6f2ec62 — regenerated pnpm-lock.yaml via pnpm install (pnpm 9.15.9, matching CI). Verified pnpm install --frozen-lockfile now passes locally.

Orthogonal note (not caused by this PR): package.json declares "engines": { "node": ">=24.0.0" } but CI pins node-version: 20 in .github/workflows/test.yml. The install currently works because pnpm treats the engines field as a warning rather than a hard constraint, but the warning will show up on every run. Worth bumping the CI matrix to Node 24 separately if you want a clean log.

[quanticsoul4772]

Pushed 6439b83 — lowered coverage thresholds to match current baseline.

CI failure cause: The thresholds I set (lines: 60%, statements: 60%, branches: 50%) were above actual measured coverage. CI reported:

• Lines: 55.32% vs 60% threshold → FAIL
• Statements: 54.21% vs 60% threshold → FAIL
• Branches: 46.39% vs 50% threshold → FAIL

Fix: Thresholds now set just below actuals to act as a regression floor:

• lines: 54% (actual: 55.32%)
• statements: 53% (actual: 54.21%)
• branches: 44% (actual: 46.39%)
• functions: 60% (unchanged, was already passing)

These values prevent coverage regressions without blocking CI on the existing codebase. Comments in the config note they should be raised as coverage improves.

[priyanshus]

@quanticsoul4772 Approved PR. Please merge it after resolving conflicts.

Thanks!

[quanticsoul4772]

@priyanshus conflicts resolved in e3c2134. CI test passed (26s, 102 tests). My account doesn't have merge permission on the repo, so the merge button is yours.