fix: set CACHE_DIR fallback when no package.json is reachable (#203)

[JohannesHoppe]

Summary

Fixes #203 — npx angular-cli-ghpages --dir=dist --branch=gh-pages in a directory with no package.json (e.g. a repo that is just a static dist/ folder) fails with:

❌ An error occurred when trying to deploy:
The "path" argument must be of type string or an instance of Buffer or URL. Received undefined

Root cause

gh-pages@6.3.0 calls find-cache-dir({ name: 'gh-pages' }) in both clean() and publish(). find-cache-dir walks up from cwd looking for package.json — if it finds none, it returns undefined. gh-pages then does path.join(undefined, filenamify(repo)) → TypeError.

The reporter's workaround npm install angular-cli-ghpages works because it creates a package.json as a side effect, which find-cache-dir can then find.

Fix

find-cache-dir honors the CACHE_DIR env var as an explicit override — when set (and not a boolean-ish 'true'/'false'/'1'/'0'), it short-circuits the package.json walk and returns path.join(CACHE_DIR, name) directly.

New helper ensureGhPagesCacheDir() in engine.prepare-options-helpers.ts:

1. Respects a user-set CACHE_DIR (no-op).
2. Probes for a reachable package.json via our own synchronous walker.
3. If none is found, sets process.env.CACHE_DIR = <os.tmpdir()>/angular-cli-ghpages-cache.

Called from engine.run() before require('gh-pages').

We probe for package.json ourselves instead of delegating to find-cache-dir because find-cache-dir captures const {env} = process at module load and is then cached in require.cache — using it as our probe makes behavior brittle under test process.env reassignment.