Admin: collapsible / multi-column config groups, help text, grouped and dependent selects

Ports the timers lane's admin schema additions unchanged (field `group`,
`showWhen`, type `switch`, `optionsRoute`) so the two branches merge
cleanly, and extends them for modules whose settings are richer than a
handful of fields:

- manifest `configGroups[name]` = { collapsed: true | false | "whenSet",
  columns: 2–4, help } — a credentials block that folds once it holds a
  saved secret, a show/hide checklist laid out as a compact grid
- `help` on any field: one line of guidance under the control
- select options may carry `group` → rendered as <optgroup>s (a folder
  tree browsable inside the select)
- `optionsDependsOn: "<key>"` refetches a select's options with that
  field's current value as a query parameter, now and on every change
- a save re-runs the card's dynamic option fetches, so a list that needed
  the just-saved credentials fills in without a page reload; a blank
  "— choose —" is no longer added when the module offers its own blank
  option

Documented in docs/MODULE-GUIDE.md.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

server.js

@@ -485,6 +485,7 @@ function adminModuleView(id) {
     hasServer: Boolean(man.server),
     enabled: isEnabled(id),
     configSchema: man.configSchema || {},
+    configGroups: man.configGroups && typeof man.configGroups === 'object' ? man.configGroups : {},
     config: values,
     passwordSet,
     mountError: entry?.error || '',
@@ -505,7 +506,7 @@ function applyConfigPatch(id, patch) {
       value = current[key] || '';
     }
     if (type === 'number') value = Number(value) || 0;
-    else if (type === 'boolean') value = Boolean(value);
+    else if (type === 'boolean' || type === 'switch') value = Boolean(value);
     else if (type === 'endpoint') {
       const src = value && typeof value === 'object' ? value : {};
       value = {