fix: replace mutable default argument in get_all_uids

[t7929375-eng]

Summary

get_all_uids() in gittensor/utils/uids.py uses a mutable default argument (exclude: List[int] = []). This is a well-known Python anti-pattern (W0102) — if any caller mutates the list, the shared default object is permanently corrupted for all subsequent calls.

Replaced with Optional[List[int]] = None and an explicit if exclude is None: exclude = [] guard.

Type of Change

• Bug fix

Testing

• ruff check passes
• pyright passes
• Self-reviewed

Checklist

• Code follows project style guidelines
• Self-review completed

cc @anderdc @LandynDev