refactor: migrate interfaces to dedicated directory

Reorganizes TypeScript interfaces into a modular structure:
- Create dedicated interfaces directory with specialized files
- Split interfaces by domain (claims, common, limits, records, user)
- Update imports in endorserServer.ts to use new interface locations
- Replace 'any' types with 'unknown' for better type safety
- Add proper type imports and exports

This improves code organization and maintainability by:
- Centralizing interface definitions
- Reducing file size of endorserServer.ts
- Making interface relationships more explicit
- Improving type safety with stricter types

src/interfaces/claims.ts

@@ -0,0 +1,63 @@
+import { GenericVerifiableCredential } from "./common";
+
+export interface AgreeVerifiableCredential {
+  "@context": string;
+  "@type": string;
+  object: Record<string, unknown>;
+}
+
+// Note that previous VCs may have additional fields.
+// https://endorser.ch/doc/html/transactions.html#id4
+export interface GiveVerifiableCredential extends GenericVerifiableCredential {
+  "@context"?: string;
+  "@type": "GiveAction";
+  agent?: { identifier: string };
+  description?: string;
+  fulfills?: { "@type": string; identifier?: string; lastClaimId?: string }[];
+  identifier?: string;
+  image?: string;
+  object?: { amountOfThisGood: number; unitCode: string };
+  provider?: GenericVerifiableCredential;
+  recipient?: { identifier: string };
+}
+
+// Note that previous VCs may have additional fields.
+// https://endorser.ch/doc/html/transactions.html#id8
+export interface OfferVerifiableCredential extends GenericVerifiableCredential {
+  "@context"?: string;
+  "@type": "Offer";
+  description?: string;
+  includesObject?: { amountOfThisGood: number; unitCode: string };
+  itemOffered?: {
+    description?: string;
+    isPartOf?: { identifier?: string; lastClaimId?: string; "@type"?: string };
+  };
+  offeredBy?: { identifier: string };
+  recipient?: { identifier: string };
+  validThrough?: string;
+}
+
+// Note that previous VCs may have additional fields.
+// https://endorser.ch/doc/html/transactions.html#id7
+export interface PlanVerifiableCredential extends GenericVerifiableCredential {
+  "@context": "https://schema.org";
+  "@type": "PlanAction";
+  name: string;
+  agent?: { identifier: string };
+  description?: string;
+  identifier?: string;
+  lastClaimId?: string;
+  location?: {
+    geo: { "@type": "GeoCoordinates"; latitude: number; longitude: number };
+  };
+}
+
+// AKA Registration & RegisterAction
+export interface RegisterVerifiableCredential {
+  "@context": string;
+  "@type": "RegisterAction";
+  agent: { identifier: string };
+  identifier?: string;
+  object: string;
+  participant?: { identifier: string };
+}