feat(core-dsr): Payload impls, recording doubles, DI binders, contract tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-dsr/src/dsr-collection-custom.ts

@@ -0,0 +1,65 @@
+import type { FieldPii } from "@repo/core-shared/payload";
+
+export type { FieldPii };
+
+/**
+ * DSR-specific Payload collection custom metadata.
+ *
+ * Collection authors annotate their collection configs with these shapes so the
+ * DSR implementations can walk `custom.subject` linkage and filter by each
+ * field's `custom.pii.exportable` flag.
+ *
+ * The `pii` map mirrors the field-level `FieldPii` shape from
+ * `@repo/core-shared/payload` so that the `pii-declaration-must-be-complete`
+ * ESLint rule is satisfied for each declared field.
+ *
+ * @example
+ * ```ts
+ * import type { DsrCollectionCustom } from "@repo/core-dsr";
+ *
+ * const ordersCollection: CollectionConfig = {
+ *   slug: "orders",
+ *   custom: {
+ *     subject: { field: "userId", kind: "owner" },
+ *     pii: {
+ *       shippingAddress: {
+ *         category: "contact-address",
+ *         purpose: ["service-delivery"],
+ *         exportable: true,
+ *         restrictable: true,
+ *       },
+ *     },
+ *   } satisfies DsrCollectionCustom,
+ * };
+ * ```
+ */
+
+export type DsrSubjectLinkKind = "self" | "owner" | "reference";
+
+export type DsrSubjectLinkage = {
+  /**
+   * Field name in this collection that contains the subject's canonical ID.
+   * For "self" collections (e.g. "users"), use the literal "id".
+   */
+  field: string;
+  /**
+   * - "self"      — this collection IS the subject record (e.g. users).
+   * - "owner"     — the subject owns these rows (e.g. orders, blog posts).
+   * - "reference" — the subject is referenced but does not own the row.
+   */
+  kind: DsrSubjectLinkKind;
+};
+
+/** Shape expected in `collection.custom` for DSR-enabled collections. */
+export type DsrCollectionCustom = {
+  /** Subject linkage metadata. Omit for collections with no subject data. */
+  subject?: DsrSubjectLinkage;
+  /**
+   * Map of field name → FieldPii metadata. Must include all required fields
+   * (`category`, `purpose`, `exportable`, `restrictable`) to satisfy the
+   * `pii-declaration-must-be-complete` ESLint conformance rule.
+   *
+   * Omit for collections with no PII fields.
+   */
+  pii?: Record<string, FieldPii>;
+};