M4-07: Recover common parameters

[DrunkOnJava]

Created from the roadmap audit in TODO.md.

Source: https://github.com/DrunkOnJava/rvt-rs/blob/main/TODO.md#L635
Tracking commit: 1ec8105

Scope

Labels: priority:P1, type:feature, area:elements, area:python

• Decode instance/type parameter values:
  • text
  • integer
  • double
  • length
  • area
  • volume
  • yes/no
  • URL
  • material
  • element id references
• Resolve type-vs-instance override precedence.

Acceptance criteria:

• CLI and Python expose parameters consistently.
• IFC property sets include common parameters.
• Viewer info panel displays them in readable form.

Definition of done

• The TODO acceptance criteria for this section are implemented or explicitly superseded by a linked decision.
• Tests, fixtures, or documentation are added at the level appropriate to the change risk.
• User-facing behavior and limitations remain honest in README/docs/viewer messaging.
• Relevant CI checks pass before the issue is closed.