FCI theming refresh, contact identity fields, Amplify secrets fix

- Remap globals.css tokens to FCI brand palette (Eggplant #801d7f,
  Spring Pea #96bc33, Seed Grant #679038, Squash #c9ad2d, FCI gray
  #4b5657). Existing leaf-* / clay-* class names preserved.
- Switch body font to Open Sans (FCI's free fallback for Museo Sans).
  Headings keep Fraunces.
- Add contact identity (first name, last name, email) as readonly
  fields at the top of Stage 0. /api/data fetches via APIv4
  Contact.get with email_primary.email join; values flow through
  FormDataPayload.contact and into the form's evalState so the
  readonly renderer displays them. Draft restore re-applies them so
  a stale local draft can't override.
- amplify.yml: fetch Amplify Secrets from SSM Parameter Store when
  they don't arrive as build-shell env vars (the common failure mode
  behind "Refusing to run in production without CIVI_*"). Adds a
  length-only diagnostic echo and a hard-fail guard so a missing
  required var stops the build with a clear message instead of
  bundling empty strings and crashing the SSR Lambda at runtime.

types/form.ts

@@ -168,6 +168,17 @@ export interface FormConfig {
   sections: StageSectionConfig[];
 }
 
+/**
+ * Identifying details for the contact submitting the form, derived from the
+ * cid resolved by /api/data. Surfaced as readonly fields in Stage 0 so the
+ * person filling out the check-in can confirm who's logged as the submitter.
+ */
+export interface ContactIdentity {
+  firstName: string;
+  lastName: string;
+  email: string;
+}
+
 /**
  * The shape returned by /api/data. Used by the form on initial load.
  */
@@ -176,6 +187,8 @@ export interface FormDataPayload {
   orgName: string;
   /** Current Framework Stage (text value). */
   currentStage: string;
+  /** Identifying details of the contact behind the cid (readonly display). */
+  contact?: ContactIdentity;
   /**
    * Per-field-most-recent prefill values, keyed by the FieldConfig.name.
    * Fields with no prior value are simply absent from this map.