test: make CLI tests cross-platform on Windows

[udaykakade25]

Path assertions in commands.test.ts assumed POSIX separators, so 9 tests failed on Windows where path.join produces backslashes. Use path.join for expected literals and normalize backslashes to forward slashes when matching mock-call paths. Runtime code unchanged.

BEFORE

The failures

All paths in the test file use /, but on Windows path.join('/test', 'my-project', ...) returns
\test\my-project..., so the matchers don't find a match.

#: 1
Test: should create project with selected resources
Expected: { from: '/test/my-project/_gitignore', to: '/test/my-project/.gitignore' }
Actual on Windows: \test\my-project_gitignore
────────────────────────────────────────
#: 2
Test: should scaffold e2e, visual, live, and eval tests for external projects
Expected: stringContaining('live/playwright.config.ts')
Actual on Windows: …\sunpeak\live\playwright.config.ts
────────────────────────────────────────
#: 3
Test: should scaffold 4 test types for JS projects
Expected: stringContaining('e2e/smoke.test.ts')
Actual on Windows: …\tests\e2e\smoke.test.ts
────────────────────────────────────────
#: 4
Test: should scaffold all test types for sunpeak projects without NOTE in live config
Expected: stringContaining('live/playwright.config.ts')
Actual on Windows: …\tests\live\playwright.config.ts
────────────────────────────────────────
#: 5
Test: should skip existing files without overwriting
Expected: stringContaining('evals/eval.config.ts')
Actual on Windows: …\tests\evals\eval.config.ts
────────────────────────────────────────
#: 6
Test: should parse command-based server into command and args
Expected: getWrittenContent(…, 'sunpeak/playwright.config.ts')
Actual on Windows: endsWith() returns false → config is undefined
────────────────────────────────────────
#: 7
Test: should not scaffold test bodies that would fail on missing tools
Expected: getWrittenContent(…, 'live/example.test.ts')
Actual on Windows: same as above
────────────────────────────────────────
#: 8
Test: should include multi-language hints in "configure later" config
Expected: getWrittenContent(…, 'sunpeak/playwright.config.ts')
Actual on Windows: same as above

AFTER FIXES

all pnpm --filter sunpeak validate - all checks pass.