i18n gate red: help-drawer t() calls name the wrong namespace

[krisarmstrong]

./scripts/i18n/validate.sh fails check-keys.py on stem main:

::error::4 t() call(s) reference keys missing from EN locale:
  ui/src/components/help-drawer/GlossaryTab.tsx:48: t('common:glossary.introSimple') — not in common.json
  ui/src/components/help-drawer/GlossaryTab.tsx:48: t('common:glossary.introTechnical') — not in common.json
  ui/src/components/help-drawer/GlossaryTab.tsx:73: t('common:glossary.related') — not in common.json
  ui/src/components/help-drawer/TestsTab.tsx:54: t('common:tests.intro') — not in common.json

The same four keys are simultaneously reported as unreferenced in help.json — so the keys exist, the call sites just name common: instead of help:. At runtime these render the raw key string in both locales.

Also reported unused, needing a decision (wire up or delete):
common.json: tooltips.header.{help,history,logout,refresh,settings}

Found while landing Step 3.5; predates it.