Registry: fixed-digit Version + immutable version_digits

[AgentDosaku]

Summary

• add a dedicated Version value object with fixed-digit parsing, normalization, and ordering
• integrate version handling into Registry and _RegistryCore
• add immutable version_digits registry metadata (validated like mutable and version_objects)
• enforce strict digit-width validation (e.g. digits=1 rejects 1.0)
• align registry and local jobs tests with canonical version formatting

Validation

• ds test --unit tests/unit/mindtrace/registry
• ds test --unit

Notes

• rebased onto latest dev before final test run
• draft PR for discussion first

Usage examples

Version class

from mindtrace.registry.core.types import Version

v1 = Version("1", digits=3)
v2 = Version("1.0", digits=3)
assert v1 == v2
assert str(v1) == "1.0.0"
assert str(v1.bump()) == "1.0.1"

Registry with immutable version_digits

from mindtrace.registry import Registry

# First creation sets immutable registry metadata
registry = Registry("./my_registry", version_objects=True, mutable=False, version_digits=1)
registry.save("model:classifier", model, version="1")

# For digits=1, dotted versions are rejected
# registry.save("model:classifier", model, version="1.0")  # ValueError

# Reopening with conflicting version_digits raises ValueError
# Registry("./my_registry", version_objects=True, mutable=False, version_digits=3)