The previous callout said "secrets must be re-entered on each full
save", which contradicted the field-level hint "leave blank; the
saved value stays". The actual contract: empty secret = keep saved
value (backend apply merge), required only on first setup.
Rewrite the callout (web/index.html + web/config.js, zh/en) to three
short sentences and make it consistent with secret.keepSet /
telegram.workerHint:
- Secrets are stored server-side and never echoed.
- Leave a secret blank to keep its saved value; required on first
setup.
- Other fields are read back automatically.
Dropped the "sent as <code>null</code>" sentence (too technical; field
hints already cover it) and removed the orphaned <code>null</code>
element. Dropped "always uses the primary account" -- the SPA has no
account_id field to move it to, so it is removed from the callout.
No JS logic changes; applyI18n just sets textContent on [data-i18n]
elements, so the <code> removal is safe. GATE-DOCS 6/6 PASS.