fix: make path checks and tool output cross-platform on Windows

[Arthur742Ramos]

Summary

Three production bugs broke this package completely on Windows because path-separator handling assumed POSIX. CI is ubuntu-latest only, so they were invisible there. Found while running npm test on Windows — 21 unit tests + 1 e2e test fail on main.

Production bugs fixed

#	File	Bug	Effect on Windows
1	src/ingest.ts:183	clonePath.startsWith(${tempRoot}/) — resolve() returns \ separators	Every clone fails with Unsafe clone path
2	src/web/routes.ts:447	Same startsWith(prefix + "/") pattern	Every file download returns 400
3	src/tools.ts:248	line.replace(context.repoPath + "/", "") doesn't strip on Windows	Search results sent to LLM contain absolute repo paths instead of relative

Plus a polish fix: list_files now normalizes displayed paths to forward slashes so they match what the tool description tells the LLM to use ('src/index.ts').

Approach

• New src/utils.ts helpers:
  • isPathInsideDir(parent, child) — resolves inputs internally, uses path.relative (the same correct pattern safePath already uses in tools.ts).
  • toPosixPath(p) — for display normalization, mirroring what src/impact.ts:74 already does.
• src/tools.ts search was rewritten to invoke ripgrep with cwd: repoRoot + a relative target + --path-separator /. This eliminates the path-stripping shim entirely and makes output deterministic on both platforms (rubber-duck suggested this approach over parsing path:line:col:text text output, which is fragile when paths contain : like C:\…).

Test fixes

The 21 failing tests were all test-only assertion bugs — production code correctly used path.resolve/path.join, but the assertions baked in POSIX-only forms like "/repo/src/index.ts" and p.endsWith("/custom/file.md"). Switched them to path.resolve(...) / normalized predicates so they work on either platform.

The 1 e2e failure (cache-command.e2e.test.ts) was caused by the test setting HOME to redirect ~/.cache — but Node's os.homedir() reads USERPROFILE on Windows. Fixed in the shared runCli helper by mirroring HOME → USERPROFILE on Windows, so future tests get this for free.

Validation on Windows

Check	Before	After
npm run typecheck	✓	✓
npm run lint	✓	✓
npm test	21 failed / 944 passed	965 passed
npm run test:e2e:cli	1 failed / 8 passed	9 passed
npm run build	✓	✓

Linux behavior is unchanged: the helpers and path.relative-based check are semantically equivalent to the old startsWith(prefix + "/") when separators are /.

Out of scope

• The file-download endpoint guard is lexical only (does not resolve symlinks). The original code had the same property; symlink hardening can be a follow-up if generated outputs ever start including symlinks.
• Adding a Windows runner to the CI matrix would prevent regressions like this — also a sensible follow-up but not part of this PR.