chore(lint): justify intentional no-control-regex (ANSI strip) + ratchet to error (#737)

The 5 no-control-regex warnings are all the same intentional ANSI-color-strip
pattern /\x1b\[[0-9;]*m/g across 5 test files. The \x1b (ESC) control char is
the required leading byte of an ANSI SGR sequence, so matching it is the whole
point of stripping color codes from captured CLI/console output. Add an inline
eslint-disable-next-line with justification at each site (not a refactor — the
control char is essential, not accidental), then flip no-control-regex from
warn to error so the debt can't regrow.

Refs #736

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

eslint.config.mjs

@@ -222,7 +222,7 @@ export default tseslint.config(
       // Downgraded from recommended error → warn (pre-existing violations; follow-up to fix)
       'no-useless-escape': 'warn',
       'no-regex-spaces': 'warn',
-      'no-control-regex': 'warn',
+      'no-control-regex': 'error',
       'no-irregular-whitespace': 'warn',
     },
   },