fix: Code review bug fixes and cleanup

[lfrancke]

Summary

Important

PR #56 should fix the cargo deny warning. So review that first.

I looked into a problem with containerdebu I found during debugging a customer.
In the course I had Claude do a sweep of the code for potential bugs. This PR fixes all of them.
You can review commit by commit as well. Each fix has its own commit.

Collection of bug fixes and code quality improvements found during code review:

• Fix GID logging bug: The tracing statement for user.gid was reading from user.uid, reporting wrong values
• Idiomatic disk empty check: Replace into_iter().next().is_none() with list().is_empty()
• Remove dead code: Stale .source() call with unused result in error reporting
• Fix typo: "proess" → "process" in error message
• Graceful error handling in loop: Replace unwrap() on JSON serialization and file write with error logging, so the long-running process doesn't crash on transient failures (e.g. disk full)
• Non-blocking sleep: Use tokio::time::sleep instead of std::thread::sleep in async context
• Graceful DNS init: Handle unreadable /etc/resolv.conf by skipping DNS lookups instead of panicking — broken DNS config is a likely scenario for a container debugging tool
• Consistent error wrapping: Network collector now returns Result, wrapped in ComponentResult by the orchestrator so errors appear in JSON output instead of being silently swallowed
• Deterministic JSON output: Use BTreeMap instead of HashMap for stable key ordering, making output diffable across runs

Test plan

• cargo test --all-features passes
• cargo clippy with RUSTFLAGS="-D warnings" passes
• cargo fmt applied

[NickLarsenNZ]

LGTM

[NickLarsenNZ]

Thanks for breaking into specific commits. Made it easy to review.

[lfrancke]

You were too fast :)
I put up another PR 56 to fix the cargo deny warning independently.

[lfrancke]

Thanks for the review! Does GitHub have a proper "commit by commit"-review mode? I thought I read something on that but couldn't find it now.

Edit: https://github.blog/changelog/2025-12-11-review-commit-by-commit-improved-filtering-and-more-in-the-pull-request-files-changed-public-preview/#%f0%9f%94%8d-review-commit-by-commit

Found it. I was more hoping for a "next commit" / "previous commit" kinda style.

[lfrancke]

Thanks Sascha. I pulled those updates out into a separate pr #56

[Techassi]

Ah, my bad. I will review the other PR then.

EDIT: I've approved #56 which is getting merged. I will rebase this PR as soon as it is merged so that we can close this one off.