Implement CE-WP-0009: wire umbrella to @citation-evidence/engine

Add link: dependency on citation-engine, retarget @shared/@engine aliases,
remove in-repo shared/engine copies. ADR-0002 accepted (option B).
172 tests, typecheck, and lint pass.

docs/decisions/ADR-0002-monorepo-vs-polyrepo.md

@@ -1,16 +1,19 @@
 # ADR-0002 — Monorepo vs polyrepo for the six subsystems
 
-- Status: proposed
+- Status: accepted
 - Date: 2026-05-24
-- Workplan: CE-WP-0001-T07 (stub)
+- Decided: 2026-06-22
+- Workplan: CENG-WP-0002-T01
 
 ## Context
 
 The umbrella-first MVP lives entirely in `citation-evidence/` under
-`src/{shared,engine,anchor,source,binder,work,app}/`. Each folder is named
-after its eventual extracted package. At some point — driven by an external
-consumer needing one subsystem, or by independent release cadence — code
-will move out into its sister repo.
+`src/{anchor,source,binder,work,app}/` with shared types and engine services
+in the extracted `@citation-evidence/engine` package (`citation-engine` repo).
+
+Each remaining folder is named after its eventual extracted package. At some
+point — driven by an external consumer needing one subsystem, or by independent
+release cadence — code will move out into its sister repo.
 
 We need a written answer to: when that moment comes, do we (a) keep one
 repository with pnpm workspaces, (b) split into six independent repos with
@@ -43,8 +46,29 @@ across the boundary.
 
 ## Decision
 
-(blank — to be answered before the first subsystem extraction lands.)
+**B — six independent repos with published packages**, using **`link:` sibling
+dependencies during local development** until a registry is configured.
+
+Rationale:
+
+1. The ecosystem is already organized as six sister repos plus the umbrella;
+   independent repos match the documented architecture.
+2. `citation-engine` extraction (`CENG-WP-0001`) and umbrella wireup
+   (`CE-WP-0009`) prove the `link:../citation-engine` dev workflow.
+3. Publishing can be deferred — no registry is configured yet — without
+   blocking extraction of the remaining subsystems.
+4. Option C adds tooling overhead before any external consumer exists.
 
 ## Consequences
 
-(blank)
+- **Local dev:** sister repos sit as siblings under `~/` (or equivalent).
+  Consumers declare `"@citation-evidence/engine": "link:../citation-engine"`.
+- **Publishing:** when a registry is chosen, bump `@citation-evidence/engine`
+  semver and replace `link:` with the registry version in consumer repos.
+- **Contracts:** `citation-evidence/wiki/SharedContracts.md` stays authoritative;
+  `citation-engine/wiki/SharedContracts.md` is a conformance copy (see
+  `citation-engine/wiki/README.md`).
+- **Versioning:** engine package semver tracks API/contract changes; umbrella
+  and sister repos pin or range-pin on publish.
+- **CI:** each repo runs its own test/lint pipeline; cross-repo integration
+  tests remain in `citation-evidence` until subsystems extract fully.

docs/mvp-workplans-index.md

@@ -21,8 +21,8 @@ CE-WP-0008 fixes capture field value persistence and viewport scroll reliability
 | Workplan | Repo | Title | Status |
 |----------|------|-------|--------|
 | `CENG-WP-0001` | citation-engine | Extract engine from umbrella | done |
-| `CE-WP-0009` | citation-evidence | Wire umbrella to `@citation-evidence/engine` | active |
-| `CENG-WP-0002` | citation-engine | Package distribution (ADR-0002, publish prep) | active |
+| `CE-WP-0009` | citation-evidence | Wire umbrella to `@citation-evidence/engine` | done |
+| `CENG-WP-0002` | citation-engine | Package distribution (ADR-0002, publish prep) | done |
 
 `CE-WP-0009` depends on `CENG-WP-0001`. `CENG-WP-0002` can run in parallel;
 publish tasks wait on ADR-0002 resolution.