Implement DecisionTable versioning rules (VR-05)

[ahouseholder]

Summary

Add formal versioning rules for DecisionTable objects (VR-05-001 through
VR-05-007) as specified in specs/versioning.yaml. DecisionTable objects
currently carry a version field but no documented rules govern when and
how that version must change. This closes the gap identified in idea #1143.

Acceptance Criteria

• AC-1: Runtime or construction-time validation raises an error (or
  warning) when a DecisionTable's version is not updated consistently with
  VR-05-003 (major: input DP added/removed, or constituent DP major bump).
• AC-2: Documentation or validator enforces VR-05-004 (minor: any
  constituent DP minor bump propagates to table minor).
• AC-3: Documentation or validator enforces VR-05-005 (patch: constituent
  DP patch bump or name/description change propagates to table patch).
• AC-4: All existing concrete DecisionTable objects in
  src/ssvc/decision_tables/ carry versions consistent with VR-05-003
  through VR-05-005 relative to their current constituent DP versions.
• AC-5: VR-05-006 pre-stability (v0.x) exemption is documented and
  reflected in any validator logic.
• AC-6: Notes file notes/decision-table-versioning.md is created
  with implementation guidance, worked version-propagation examples, and
  migration notes for existing tables.
• AC-7: Unit tests cover the major/minor/patch propagation rules.

Reference

Spec: specs/versioning.yaml (VR-05 group)
Docs PR: #1144
Idea: #1143