fix: resolve home directory via cross-platform helper (partial #68)

[mvanhorn]

Summary

InitCommand and YamlConfigProvider read getenv('HOME') directly to expand the leading ~ in the default config path. On Windows that env var is usually unset (the OS uses USERPROFILE, with HOMEDRIVE + HOMEPATH as a documented fallback for shells / containers that strip USERPROFILE), so ~/.config/work-reporter/... quietly resolved to /.config/work-reporter/... at the filesystem root and init + work:report silently misbehaved.

What changed

• New Igancev\WorkReporter\Platform\HomeDirectory::resolve() helper that returns the canonical home directory per platform: HOME on POSIX, USERPROFILE on Windows with the documented HOMEDRIVE + HOMEPATH fallback. Returns an empty string when nothing is set so callers see the same shape as the prior (string)getenv(...) cast (no behavior change in error reporting paths).
• src/Cli/InitCommand.php: swap the bare getenv('HOME') for HomeDirectory::resolve().
• src/Config/YamlConfigProvider.php: same swap.
• tests/Unit/Platform/HomeDirectoryTest.php: per-platform branches: POSIX returns HOME, Windows prefers USERPROFILE even when HOMEDRIVE+HOMEPATH are set, Windows falls back to HOMEDRIVE+HOMEPATH when USERPROFILE is empty, and all-unset returns "". Each test skips on the other OS family; cross-OS assertions exercise on a future Windows CI lane.

Scope

This is a partial fix for #68 — only the env-var handling item on the checklist. The remaining items (Windows binary build workflow, README install section, Windows binary smoke test) are intentionally left for follow-up PRs so each item stays atomic per CLAUDE.md / CONTRIBUTING.md guidance. Happy to take any of those in a follow-up if you want.

Verification

Local (macOS / PHP 8.5):

vendor/bin/phpunit tests/Unit/Platform/HomeDirectoryTest.php
# 4 tests, 2 assertions, 2 skipped (Windows-only branches)

vendor/bin/phpunit tests/Unit/InitCommandTest.php tests/Unit/Config/YamlConfigProviderTest.php
# 27 tests, 63 assertions, no regressions

make cs            # 72/72 files clean
make stat-analyze  # phpstan 0 errors

Closes part of #68 (env-var handling only).

[igancev]

Thanks for the PR, @mvanhorn, and sorry for the delay — I've been a bit busy lately. I'll go through your proposal soon. Really appreciate your contribution!

[igancev]

Reviewed and merged - looks clean, nice refactoring. No critical issues found. Thanks for the contribution, @mvanhorn ! 👍

[mvanhorn]

Appreciate the merge @igancev, the cross-platform home directory helper makes the reporter portable.

[mvanhorn]

Thanks @igancev! The cross-platform home directory helper should hold up on Windows too.