Form: required submitter info section above the stage pathway

Captures the form-filler's name and email on every check-in. Both fields
are required; values write back to Check_in_data__organizing_.Survey_completed_by
and Survey_completed_by_email on the activity, giving us a per-submission
record of who filled out which check-in.

Implementation:
- config/form.ts: new submitterInfo section (rank -1) at the head of the
  sections array. rank -1 keeps it out of the past/current/future stage
  pathway computation.
- components/EngagementForm.tsx: filter the submitter section out of
  sectionsToRender and render it directly with FieldRenderer inside a
  bordered card above the stage list. The fields still flow through RHF
  registration, onInvalid scroll-to-error, and the onSubmit visibility
  filter the same as any other field.

The staff report auto-discovers these fields via CustomField.get since
they live in Check_in_data__organizing_, so the field history shows up
in the report with no extra wiring.

config/form.ts

@@ -54,6 +54,36 @@ const G5 = "Stage_5";
 // route through Contact.update on submit and Contact.get at form load.
 const G_ORG = "Food_Co_op_Organizing";
 
+// Submitter information — captured on every check-in. Rendered above the
+// stage pathway (see EngagementForm) so it's not threaded into the past /
+// current / future stage rail. Both fields are required on every submission.
+// rank: -1 keeps the section out of the rank-based pathway computation;
+// EngagementForm filters this section out of `sectionsToRender` and renders
+// it directly via FieldRenderer above the stage list.
+const submitterInfo: StageSectionConfig = {
+  rank: -1,
+  id: "submitter_info",
+  label: "Survey submitter",
+  intro:
+    "Who's filling this out? We log this with each submission so we can follow up if needed.",
+  fields: [
+    {
+      name: "Survey_completed_by",
+      label: "Survey completed by",
+      type: "text",
+      required: true,
+      civiField: `${G0}.Survey_completed_by`,
+    },
+    {
+      name: "Survey_completed_by_email",
+      label: "Survey completed by — email",
+      type: "email",
+      required: true,
+      civiField: `${G0}.Survey_completed_by_email`,
+    },
+  ],
+};
+
 // Stage 0 — Survey (always visible)
 const stage0: StageSectionConfig = {
   rank: 0,
@@ -753,7 +783,7 @@ export const formConfig: FormConfig = {
   subtitle:
     "Thank you for updating your co-op information. The questions you'll see depend on where you are in the Framework.",
   stageField: "current_stage",
-  sections: [stage0, stage1, stage2, stage3, stage4, stage5],
+  sections: [submitterInfo, stage0, stage1, stage2, stage3, stage4, stage5],
 };
 
 /** Convenience: flatten all field configs across all sections for lookup by name. */