Refresh the codebase metrics page, and drop the 36 project words cspell no longer needs

Problem/Motivation

The codebase metrics page was last measured on 2026-09-21, before the pre-release audit changes of the last two days landed on 1.x.

.cspell-project-words.txt lists 60 words, and 36 of them no longer do anything:

• the word no longer appears in any file the cspell job checks: bovigo, cellspacing, finalizer, roboto, segoe;
• it appears only under .tugboat/ or in logo.svg, which the job does not check: chgrp, hreflang, inkscape, mergerequest, tugboatqa;
• the job adds it itself: mkdocs, and webform as part of a submodule machine name;
• core's dictionaries hold it: addtogroup, docroot, drush, français, hmac, langcode, msgctxt, olivero, referer, subform, uncacheable, unindexed;
• one of the dictionaries the job enables accepts it: camunda, casey, dave, delegator, erin, hostnames, openapi, oscar, retryable, rita, upsert, varchar.

A list that holds words nobody needs can no longer say which words the project actually coined.

Proposed resolution

• Remove those 36 words, leaving 24. The cspell job is the authority: any word its report names is put back.
• Regenerate docs/metrics.md from the branch, as the last commit, so the metrics job reproduces it.

AI-Generated: Yes (Claude Code drafted this issue summary and wrote the change on the merge request.)