Extract engine from citation-evidence umbrella (CENG-WP-0001)

Bootstrap @citation-evidence/engine as a standalone TypeScript package
with shared types and engine services copied from the umbrella MVP.
All 89 tests pass with lint and typecheck clean.

README.md

@@ -1,19 +1,44 @@
 # citation-engine
 
-Domain model and tooling for citations — the shared vocabulary
-(`Document`, `Selector`, `Annotation`, `EvidenceItem`, `EvidenceLink`,
-`EvidenceSet`, state enums, branded IDs, canonical text normalization)
-together with the services and repositories that act on it.
+Core domain model and engine services for the citation-evidence ecosystem.
 
-## MVP status: INTENT only
+This package provides the shared vocabulary (`Document`, `Selector`, `Annotation`,
+`EvidenceItem`, `EvidenceLink`, `EvidenceSet`, state enums, branded IDs,
+canonical text normalization) together with in-memory repositories, orchestration
+services, the event bus, and citation card renderers.
 
-During the citation-evidence MVP, code lives upstream in
-[`citation-evidence`](../citation-evidence/) under `src/shared/` and
-`src/engine/`. This repo currently holds `INTENT.md` describing what will
-move here once the engine API stabilises. Until extraction, contract
-changes belong in
-[`citation-evidence/wiki/SharedContracts.md`](../citation-evidence/wiki/SharedContracts.md),
-not here.
+## Layout
 
-The dependency map (`citation-evidence/wiki/DependencyMap.md`) marks this
-package as a **leaf node**: nothing internal depends on anything else.
+```
+src/
+  shared/   # types, enums, pure helpers
+  engine/   # services, repositories, rendering, persistence
+wiki/
+  SharedContracts.md   # conformance reference (enum lists, normalization rules)
+```
+
+## Development
+
+```bash
+pnpm install
+pnpm test
+pnpm typecheck
+pnpm lint
+```
+
+## Extraction status
+
+Code was extracted from `citation-evidence/src/shared/` and `citation-evidence/src/engine/`
+after the umbrella MVP (CE-WP-0001..0008) stabilized. The umbrella repo still carries
+a copy during the transition; this repository is the canonical home going forward.
+
+Contract changes belong in `citation-evidence/wiki/SharedContracts.md` first, then
+sync to `wiki/SharedContracts.md` here.
+
+## Related repos
+
+- [`citation-evidence`](../citation-evidence/) — umbrella reference workspace
+- [`evidence-anchor`](../evidence-anchor/) — selector creation and resolution
+- [`evidence-source`](../evidence-source/) — document ingestion
+- [`citation-work`](../citation-work/) — review workspace UX
+- [`evidence-binder`](../evidence-binder/) — evidence-to-field linking