chore(ui-tooling): drop the page-key read census its card closed as not planned

ui/scripts/page-key-read-census.mjs and its test were the instrument a
renderer-vs-PageSchema page-key gate would have read (objectui#9438). That
card was closed not planned on 2026-09-22, no gate reads the census, and
only its own test and the `census:page-key-reads` alias named it.

Co-authored-by: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012eXtKYmXEnCc1GExP4go12

Author: claude

ui/package.json

@@ -50,7 +50,6 @@
     "census:body-dialect-producers": "node scripts/body-dialect-producer-scan.mjs",
     "census:tsconfig-test-parity": "node scripts/tsconfig-test-parity-census.mjs",
     "census:cross-file-line-citations": "node scripts/cross-file-line-citation-census.mjs",
-    "census:page-key-reads": "node scripts/page-key-read-census.mjs",
     "census:dollar-dialect-aliases": "node scripts/dollar-dialect-alias-census.mjs",
     "census:changeset-polarity": "node scripts/changeset-polarity-census.mjs",
     "check:new-line-citations": "node scripts/check-new-cross-file-line-citations.mjs",