fix: update_dataset_metadata handles partial update dicts without KeyError

[Copilot]

update_dataset_metadata used direct key access on the updates dict, requiring callers to supply all four fields (description, cached, anonymize, transcribed) even when only updating one. A partial dict like {"description": "new desc"} would raise KeyError: 'cached', caught and surfaced as "Invalid metadata key: 'cached'" — misleading since cached is valid, just absent.

Changes

• src/voxkit/storage/datasets.py — replace four separate updates["field"] guards with a single loop using field in updates membership check:

  # Before
  if updates["description"] is not None:
      metadata["description"] = updates["description"]
  # ... repeated for each field
  
  # After
  for field in ("description", "cached", "anonymize", "transcribed"):
      if field in updates and updates[field] is not None:
          metadata[field] = updates[field]

  Also drops the stale KeyError from the Raises docstring.

• tests/storage/test_datasets.py — adds test_update_dataset_metadata_missing_keys passing a genuinely partial dict (keys entirely absent, not just None) and asserting only the provided field changes.

Testing

• Test testable logic
• Edge cases addressed

Testing Notes: Existing tests already covered None-value passthrough; new test covers the actual bug path (absent keys). Logic validated in isolation against both old and new behavior.

Documentation

• README updated (if applicable)
• Code comments added/updated
• User-facing documentation updated (if applicable)

Documentation Notes: Removed misleading KeyError from Raises docstring.

Checklist

• Code follows project conventions
• No breaking changes (or documented if intentional)
• All CI checks pass

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• astral.sh
  • Triggering command: /usr/bin/curl curl -LsSf REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[BeckettFrey]

LGTM