feat(config): warn! on bad source paths instead of hard fail

[gabeschine]

Fixes #2395

Wraps the per-source and per-paths file config resolver in individual methods whose overall result is examined for success. On failure, a warn!() is emitted, but iteration continues.

To-do:

• Add a test.

[gabeschine]

@CommanderStorm do you have a recommendation for how/where I should add a regression test?

[Copilot]

Pull request overview

This PR changes Martin's configuration file handling to gracefully handle invalid source paths by logging warnings instead of failing hard. This improves robustness when some configured sources are temporarily unavailable or misconfigured.

Key Changes:

• Extracted source resolution logic into two new helper functions: resolve_one_source_int for individual sources and resolve_one_path_int for path-based sources
• Wrapped source resolution calls in match statements that catch errors and log warnings instead of propagating failures
• Maintains all existing functionality while allowing the server to start even when some sources cannot be resolved

[gabeschine]

I've added a simple unit test to catch any possible regressions for this feature.