Handle clients that advertise workspaceFolders but fail workspace/workspaceFolders (fixes #70)

[csacca]

Summary

• Prevent server crashes when a client claims workspaceFolders capability but returns error/null for workspace/workspaceFolders.
• Treat request error/null as no folders; prefer InitializeParams.workspaceFolders when present; log a warning.
• Start PathSynchronizer only after a successful folders fetch.

Repro

• See Crash when client advertises workspace/workspaceFolders but doesn’t implement handler #70 for minimal steps and environment.

Changes

• Defensive handling around getWorkspaceFolders at call sites:
  • src/lifecycle/MatlabSession.ts
  • src/lifecycle/PathSynchronizer.ts
  • src/indexing/WorkspaceIndexer.ts
• Cache folders from InitializeParams for later use.
• Tests covering: capability=false, success path, error path.

Notes

• Developed against a release tag; changes rebased/cherry‑picked onto main for this PR.
• No breaking API changes.

[dklilley]

Thanks for reporting and working to resolving this!

I will review this as soon as I can, but it may not be until next week due to current commitments. Thanks for your patience!