feat(agents): wire domain reviewers into ship-feature(-lane) review stage

Route Stage 4 / review-phase reviews to ccam:backend-reviewer,
ccam:frontend-reviewer, ccam:mcp-reviewer (parallel to the generic Code
Reviewer) by which of server/, client/, mcp/ the diff touches. Give each
reviewer a parseable verdict line and project memory to match qc-local's
rigor, and update docs/LANES.md's per-stage agent description accordingly.

skills/ship-feature/SKILL.md

@@ -97,8 +97,23 @@ you dropped back to.
   a reviewer. It runs the **code-review** skill on the working diff
   (see also **superpowers:requesting-code-review** for what to hand over).
   Final line: `REVIEW: CLEAN` or `REVIEW: FINDINGS — <n>`.
-- Apply what is worth applying with **superpowers:receiving-code-review**
-  judgment: verify each point, neither blind agreement nor blind rejection.
+- **Domain reviewers, in parallel with the above (same message, separate
+  Agent calls).** Check `git diff --name-only` (against the base this task
+  started from) for touched layers and launch every matching one —
+  FOREGROUND, fresh context, never `fork`, addressed as `ccam:backend-reviewer`
+  / `ccam:frontend-reviewer` / `ccam:mcp-reviewer`:
+  - Any path under `server/` → `ccam:backend-reviewer`.
+  - Any path under `client/` → `ccam:frontend-reviewer`.
+  - Any path under `mcp/` → `ccam:mcp-reviewer`.
+  - None of those three touched → skip all three; the generic Code Reviewer
+    above is the only gate.
+  - Hand each ONLY the repo path and the working diff — each scopes itself to
+    its own domain's files. Each ends with its own parseable line:
+    `BACKEND-REVIEW:` / `FRONTEND-REVIEW:` / `MCP-REVIEW:` — `CLEAN` or
+    `FINDINGS — <n>`.
+- Apply what is worth applying — the generic review plus every domain
+  reviewer that ran — with **superpowers:receiving-code-review** judgment:
+  verify each point, neither blind agreement nor blind rejection.
 - Changed code in response? Re-run the `tests` phase.
 
 ### gate — evidence before the completion claim