Reduce redundant ECS geometry synchronization consultations on renderer reads

## Problem

The #15977 investigation measured roughly 929,000 geometry refresh/content-size consultations in a 10.5-second workload with zero geometry-version misses. Bypassing repeated property synchronization recovered about 5%, so this is a bounded independent cost rather than the redraw-loop root cause.

## Goal

Remove redundant geometry synchronization work without weakening ECS/store authority or extension compatibility.

## Proposed Solution

Instrument consultation sources, define the cache-hit invariant, and avoid repeated synchronization when the geometry version and relevant inputs are unchanged.

## Acceptance Criteria

- A deterministic benchmark reproduces the consultation count.
- The dominant call sites and cache-hit contract are documented.
- The optimized path materially reduces consultations and renderer task occupancy.
- Geometry, serialization, undo, and compatibility tests remain green.