Name the monospace faces once, as a typeface token and md-mono

Both applications show values a person reads or types character by
character: SealShare's share tokens and recovery codes, ReStride's file
and folder names and its keyboard shortcuts. The package wrote the
platform's monospace stack twice (the reset's <code>, <kbd>, <samp> and
the mono field) and gave everything else nothing, so an app copied the
stack by hand. --md-ref-typeface-mono now holds it, read by the reset,
the field and a new md-mono text class; the guard points font-mono at
<code> or md-mono. Not an M3 token: M3 names a brand and a plain
typeface and nothing for code. Decided with the user (plan step 46).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

resources/css/foundation/reset.css

@@ -78,7 +78,7 @@
     kbd,
     samp,
     pre {
-        font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
+        font-family: var(--md-ref-typeface-mono);
         font-feature-settings: normal;
         font-variation-settings: normal;
         font-size: 1em;