feat(config): add LogDir and move diagnostic logs to XDG state

[jcnnll]

Problemn Being Solved

Diagnostic logs are currently written to the user's configuration directory (~/.config/lstk). This mixes persistent configuration with diagnostic state, which clutters the config tree and doesn't follow standard OS conventions for logs.

Changes

• Add LogDir() to resolve to XDG and Windows standard logging paths
• Decoupled logging from configuration
• Updated CLAUDE.md to follow the logging standard
• Added integration test to cover this feature

Tests

• Added TestLogDir in internal/config/paths_test.go.
• The test logic is cross-platform, verifying both Windows and Unix branches.
• Verified with make test.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[gtsiolis]

Thanks for contributing, @jcnnll! ❤️

Heads-up: The team is sorting out a contribution policy process for this repository, we will follow up here as soon as we have clarity on next steps. Thanks for your patience. ⏳

[jcnnll]

Thanks @gtsiolis for responding to this PR, I totally understand the situation and look forward to being able to contribute as an when the policy has been clarified in terms of community contributions.

[gtsiolis]

Thanks for your patience, @jcnnll! ❤️

Closing this as the team decided to restrict code contributions from outside collaborators in #454.

From README.md:

You can read the source, build it, and fork it freely — but we don't accept pull requests from outside collaborators.

The best way to participate is to open a well-formed issue. A bug report we can reproduce is worth more to us than a patch, because it captures the part we can't discover ourselves

From CONTRIBUTING.md:

[...] Why we don't accept outside pull requests

lstk's architecture and roadmap move quickly, and reviewing outside patches requires context and coordination we cannot currently offer fairly. An issue lets us validate the problem and decide on an approach before anyone spends time implementing it.