docs(audit): spec enum ↔ renderer coverage audit for #2901 (#2937)

Audits every named enum export in `@objectstack/spec@16.0.0-rc.0` `ui/` against
its renderer counterpart, in both directions, plus field types and filter
operators. 24 confirmed Direction A gaps that produce a user-visible defect, 11
inert ones, 10 surfaces carrying renderer-local dialect.

Corrects the issue's premise: `ChartTypeSchema` is 19 values in the spec, not 7.
The 7-value list is an objectui fork re-exported under the spec's own symbol
name — one of five such forks.

Triaged by runtime symptom rather than by direction, because that orders the
work by how long a defect survives undetected: silently-wrong output (6) is
worse than the silently-absent case (15) that prompted #2897, and the loud
red-box tier (3) is cheapest precisely because it cannot hide.

Refs #2901, #2897, #2231, #2731

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang