Stage 0: org-contact custom fields (Food_Co_op_Organizing)

Adds four fields from the Organization Contact's Food_Co_op_Organizing
custom group to the Stage 0 (always-visible) section:

  Date Incorporated                (date, editable)
  Name on Incorporation Certificate (text, editable)
  Certificate of Incorporation     (readonly; see note)
  Equity share                     (currency, editable)

These live on the Organization Contact record, not on the Check-in
activity, so they read/write through a different code path:

  - FieldConfig gains civiContactField, mutually exclusive with civiField
  - /api/data extends the org Contact.get select to include them and
    merges values into the prefill payload keyed by form-side name
  - /api/submit splits incoming values: contact-bound fields go through
    Contact.update (run first), activity-bound fields stay in the
    Activity.create call (run second)
  - FieldRenderer readonly branch now detects file-shaped values
    ({id, file_name}) and displays the filename rather than [object Object]

Certificate_of_Incorporation is wired readonly only: the form's
file-upload pipeline is not actually wired end-to-end (FileList drops
at JSON.stringify in onSubmit; no /api/upload endpoint exists). A
follow-up will close that gap.

Also adds scripts/inspect-org-custom-fields.mjs, a one-off introspection
script for dumping CustomField metadata when wiring a new group.

app/api/data/route.ts

@@ -163,12 +163,31 @@ export async function GET(req: NextRequest) {
   }
   const orgId = orgs[0].contact_id_b;
 
+  // Org-contact custom fields configured on form fields. Each
+  // FieldConfig.civiContactField is `<group_name>.<field_name>` and is
+  // selected directly off the Organization Contact record.
+  const orgContactFieldRefs = allFields
+    .map((f) => f.civiContactField)
+    .filter((s): s is string => Boolean(s));
+  // For file-typed org-contact fields, also pull the joined .file_name so
+  // we can surface a human-readable filename in the readonly indicator.
+  const orgContactFileRefs = allFields
+    .filter((f) => f.type === "file" || (f.type === "readonly" && f.civiContactField?.toLowerCase().includes("certificate")))
+    .map((f) => f.civiContactField)
+    .filter((s): s is string => Boolean(s));
+  const orgContactSelect = [
+    "id",
+    "display_name",
+    ...orgContactFieldRefs,
+    ...orgContactFileRefs.map((ref) => `${ref}.file_name`),
+  ];
+
   // Fire org-name lookup, contact-identity lookup, stage-bearing-activity
   // lookup, prefill walk, and option-group fetch in parallel — they're
   // independent.
   const [orgRes, contactRes, stageActivityRes, { values: prefill }, options] = await Promise.all([
-    civi<{ id: number; display_name: string }>("Contact", "get", {
-      select: ["id", "display_name"],
+    civi<{ id: number; display_name: string; [key: string]: unknown }>("Contact", "get", {
+      select: orgContactSelect,
       where: [["id", "=", orgId]],
     }),
     // Identifying details for the form-filler. APIv4 lets us chain through
@@ -216,6 +235,27 @@ export async function GET(req: NextRequest) {
       }
     : undefined;
 
+  // Merge org-contact custom-field values into prefill, keyed by form-side
+  // field name. Activity-based prefill values take precedence only when an
+  // explicit non-empty entry exists — but org-contact fields don't appear
+  // in the activity walk, so collisions can't happen in practice.
+  for (const f of allFields) {
+    if (!f.civiContactField) continue;
+    const raw = org[f.civiContactField];
+    if (raw === null || raw === undefined || raw === "") continue;
+    if (f.type === "file" || f.type === "readonly") {
+      // File or readonly fields: surface as {id, file_name} so the renderer
+      // can show a filename indicator. Plain readonly text fields fall
+      // through to the else branch.
+      const fname = org[`${f.civiContactField}.file_name`];
+      if (typeof fname === "string" && fname) {
+        prefill[f.name] = { id: raw, file_name: fname };
+        continue;
+      }
+    }
+    prefill[f.name] = raw;
+  }
+
   const payload: FormDataPayload = {
     orgName: org.display_name,
     currentStage,