skip unsupported languages instead of crashing

[LckyLke]

Running gitnexus analyze on a repository containing files in a language whose tree-sitter grammar is unavailable (e.g. Swift when running git nexus analyze on pytorch repo) crashes with Error: Unsupported language: swift instead of skipping the file.

loadLanguage throws when a grammar is missing, and several callers (heritage-processor.ts, import-processor.ts, call-processor.ts) don't catch it. The worker-local setLanguage in parse-worker.ts has the same issue.

The pipeline already warns about unavailable languages upfront, so these files should be silently skipped downstream.

For Issue: #155

[vercel]

@LckyLke is attempting to deploy a commit to the NexusCore Team on Vercel.

A member of the Team first needs to authorize it.

[jecanore]

@LckyLke, PR #301 completes the unsupported language handling you started here. I built on the isLanguageAvailable() approach from PR #188 (which merged after yours) and extended it to the sequential parsing path and worker path that were still unguarded. Your boolean-return API design was cleaner — I went with guards to stay consistent with what's already merged, but appreciated the thoroughness of your approach. 🙌