docs(architecture): codify live-overrides drag protocol + floorplan per-node perf

Capture the durable patterns from the placement-interaction overhaul so reviews
and new devs don't regress them:

- tools.md: new "Data-driven live drag" section — kinds whose geometry is
  recomputed from fields (wall/opening/endpoint) preview via useLiveNodeOverrides
  (merged by getEffectiveWall/getEffectiveNode), store written once on commit;
  per-tick useScene.updateNodes is the documented anti-pattern (churns the nodes
  ref → app-wide re-render flood). Plus "Floorplan registry: per-node
  subscriptions" — each entry subscribes to its own live slice, memo'd with
  stable props, sibling-epoch invalidation; widening to the whole Map / dropping
  memo is a regression. Plus a note that the HUD snapping chip renders for any
  snap-context tool, not only those with def.toolHints.
- review SKILL.md: matching blockers in §C (data-driven drag / no per-tick store
  write) and §D (per-node list subscriptions).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.agents/skills/review-architecture/SKILL.md

@@ -120,6 +120,7 @@ If the PR adds or modifies a node kind, check against `wiki/architecture/node-de
 - New state added to `useViewer` must be presentation-only (selection, camera, level mode, display toggles). Editor-only state (active tool, phase, edit mode, paint preview, floorplan state) goes in `useEditor`.
 - **Node code does not import `useScene` directly.** A kind's geometry / system / tool should read and write through `SceneApi` (passed in by the framework) or `GeometryContext`. Direct `useScene.getState()` calls inside `packages/nodes/src/<kind>/` are a smell — they bypass the registry's IoC point and make the code harder to test.
 - **Live drag motion is imperative, not store-driven.** Tools must not call `useLiveTransforms.set(...)` per `grid:move` tick to animate registered parametric kinds — the selector path doesn't reliably re-render and the mesh visibly disappears mid-drag. Use `sceneRegistry.nodes.get(node.id)?.position.set(x, y, z)` instead, and commit once at the end via `useScene.temporal.getState().resume() → updateNode → pause()`. The reference implementation is `MoveRegistryNodeTool`. This is the *only* sanctioned use of imperative mesh transforms by a tool; flag any other location that does the same.
+- **Data-driven drags preview via `useLiveNodeOverrides`, never per-tick `useScene`.** A kind whose geometry is recomputed from data fields (wall `start`/`end`, opening host-cut, endpoint reshape) previews by publishing field patches to `useLiveNodeOverrides` (merged by `getEffectiveWall` / `getEffectiveNode`), writing the scene store **once on commit**. A tool that calls `useScene.updateNodes`/`updateNode` on `grid:move` (or any per-pointer-move tick) is a **blocker** — it swaps the `nodes` map ref and re-renders every `useScene(s => s.nodes)` subscriber app-wide each frame (`markDirty` per tick is fine). Grep tell: `updateNode(s)?(` in an `onGridMove`/`onMove`/`applyPreview` path under `packages/nodes/src/<kind>/`. See `wiki/architecture/tools.md` § "Data-driven live drag".
 
 ### D. Selector performance
 
@@ -127,6 +128,7 @@ If the PR adds or modifies a node kind, check against `wiki/architecture/node-de
 - Selectors that return new object or array references each call (e.g. `s => ({ a: s.a, b: s.b })`, `s => s.items.filter(...)`) without a custom equality function (shallow or custom) are re-render hazards.
 - Prefer subscribing by ID deep in the tree (one node per renderer) over subscribing to the full collection high up.
 - Inside a `<XxxPanel>` (legacy or `parametrics.customPanel`-mounted), avoid `useScene(s => s.nodes[selectedId])` as a callback dep — it changes every tick and pushes `useCallback` into infinite-loop territory. The recipe is in `plans/editor-node-registry.md` under "Panel slider-drag fix recipe".
+- **Per-node list renderers subscribe per-node, not to the whole live Map.** A list that draws one child per node (`FloorplanRegistryLayer` → `FloorplanRegistryEntry`) must have each child subscribe to its **own** slice (`useLiveTransforms(s => s.transforms.get(id))` / `overrides.get(id)`) and be `memo`'d with referentially stable props; the parent subscribes only to the stable id list. Subscribing the parent or a child to the whole `transforms`/`overrides` Map, dropping a `memo`, or passing unstable props re-renders all N children every drag tick — a flood that type-checks and passes tests. Sibling invalidation goes through a per-node epoch, not a whole-layer re-render. See `wiki/architecture/tools.md` § "Floorplan registry: per-node subscriptions".
 
 ### E. Separation of concerns