fixed home dir resolution for $HOME less envs

[zackbradys]

Please check below, if the PR fulfills these requirements:

• Commit(s) and code follow the repositories guidelines.
• Test(s) have been added or updated to support these change(s).
• Doc(s) have been added or updated to support these change(s).

Associated Links:

• Partially... [feature] fallback to os.UserHomeDir if os/user.Current fails #367

Types of Changes:

• Bugfix

Proposed Changes:

• Normalize $HOME at the start of every command (PersistentPreRunE) instead of assuming it's there
• Environments like cloud-init runcmd, systemd services, and cron invoke hauler without a login shell, which leaves $HOME empty, and silently breaks credential lookup in ~/.docker/config.json
• Resolution tries user.Current() first, then falls back to os.UserHomeDir() if that fails, logging a WARN only if both come up empty... this restores and extends the fallback behavior that getCosignPath() used to have before it was replaced during the overhaul and rewrite for v2.0.1...
• Stop collapsing every credential-resolution failure in the registry auth bridge (pkg/content/registry.go) to a silent "anonymous" fallback... now we have a real resolution error such as unreadable config, corrupt JSON, missing $HOME and it now propagates instead of being random indistinguishable error messages

Verification/Testing of Changes:

Before the fix... NO $HOME set...

kiternetes01:/home/rancher # env -i PATH="$PATH" /usr/local/bin/hauler store copy --store /var/lib/harvester/defaultdisk/hauler/store/ registry://registry.kiternetes.kit
2026-07-17 18:24:56 INF edge/3.6/mariadb@sha256:4657b14c43d3a720c50fc1c484a36865fa5acc53edf560a6d597c0b8bec42c9d
2026-07-17 18:24:56 ERR error (attempt 1/3)... failed to copy config: push access denied, repository does not exist or may require authorization: authorization failed: no basic auth credentials
2026-07-17 18:25:01 ERR error (attempt 2/3)... failed to copy config: push access denied, repository does not exist or may require authorization: authorization failed: no basic auth credentials

Before the fix... $HOME set...

kiternetes01:/home/rancher # env -i HOME=/root PATH="$PATH" /usr/local/bin/hauler store copy --store /var/lib/harvester/defaultdisk/hauler/store/ registry://registry.kiternetes.
kit
2026-07-17 18:25:22 INF ranchergovernment/harvester-appliance-xfce:v1.7.2
2026-07-17 18:25:25 INF registry.kiternetes.kit/ranchergovernment/harvester-appliance-xfce:v1.7.2: digest: sha256:716f2b1c6d56904e0eafb6640c8fd5e3389f554e9402316f004edee030b61fb1 size: 864
2026-07-17 18:25:25 INF containers/nginx@sha256:02b935594b7aea4a7ffd1b701d4dfa8fff13af13152b5864f23129dd2a227a18
2026-07-17 18:25:26 INF registry.kiternetes.kit/containers/nginx@sha256:02b935594b7aea4a7ffd1b701d4dfa8fff13af13152b5864f23129dd2a227a18: digest: sha256:02b935594b7aea4a7ffd1b701d4dfa8fff13af13152b5864f23129dd2a227a18 size: 1622
2026-07-17 18:25:26 INF containers/postgresql:sha256-1f182741c1fef987502c2a18346b4db24be74d32e449a9141fb448f3e95ba2c7.att

---

After the fix... NO $HOME set...

TBD

After the fix... $HOME set...

TBD

Additional Context:

A short story from our friend claude...

Start by giving hauler a $HOME-less environment and it doesn't error, it doesn't warn, it doesn't blink.

Hauler takes over the wheel and silently decides you're anonymous.

Hauler lets you find out via a "no basic auth credentials" error that reads exactly like a server side auth bug and issue.

For THREE whole days... a line by line reading of a 3000 line script, multiple failed automation workflows, a JWT autopsy, and a CVE deep-dive...

Just for you to find out there is a bug fixable with one line... "export HOME=/root"...

[zackbradys]

Closing in favor of #672...