Implement ESRC-WP-0002/0003/0004: HTML/MD ingest, metadata, recovery

Add ingestHtml and ingestMarkdown with ADR-0003 pageless offset semantics,
PDF intrinsic metadata extraction with caller-wins merge (WP-0003), and
citation recovery primitives including re-ingest reconcile, local quote
search, and pluggable discovery hooks (ADR-0004). Mark all three workplans
finished with contract tests (80 passing).

src/recovery/re-ingest.ts

@@ -0,0 +1,33 @@
+import type { Document, DocumentRepresentation } from "@citation-evidence/engine/shared";
+
+import { reconcileFingerprint, type ReconcileResult } from "./reconcile";
+
+export interface IngestOutcome {
+  readonly document: Document;
+  readonly representation: DocumentRepresentation;
+}
+
+export type IngestFn<TOptions = void> = (
+  bytes: Uint8Array,
+  options?: TOptions,
+) => Promise<IngestOutcome>;
+
+export interface ReIngestInput<TOptions = void> {
+  readonly previous: Document;
+  readonly bytes: Uint8Array;
+  readonly options?: TOptions;
+}
+
+export interface ReIngestResult {
+  readonly outcome: IngestOutcome;
+  readonly reconcile: ReconcileResult;
+}
+
+export async function reIngestAndCompare<TOptions>(
+  input: ReIngestInput<TOptions>,
+  ingest: IngestFn<TOptions>,
+): Promise<ReIngestResult> {
+  const outcome = await ingest(input.bytes, input.options);
+  const reconcile = reconcileFingerprint(input.previous, outcome.document);
+  return { outcome, reconcile };
+}