Promote v1.0.6 fixes to main

[anumathad-o]

Summary

• Added network failure details to VecDBException so callers can see
  whether a request failed because of a timeout, DNS lookup, connection, or
  TLS/certificate problem, and whether retrying may help.
• Added get_vecdb_oauth_token for OAuth client-credentials token requests,
  with HTTPS validation, configurable TLS, timeout and proxy settings, and
  sanitized OAuthTokenError diagnostics. Updated examples/test_client.py
  to demonstrate OAuth authentication and retain a basic-auth option.
• Network failures now include distinct error codes and advice on what to
  check next.
• Removed distribute_method validation for "INMEMORY GRAPH" organization
  when distribute_params is null.
• query.top_k must now be a positive integer; booleans and fractional
  values are rejected.
• Made exception formatting resilient to unsupported, circular, and deeply
  nested diagnostic values while keeping sensitive data redacted.