feat(mcp): natural-language measurements for tool inputs via @pascal-app/lingo

Measurement/angle parameters on the scene tools now accept a bare number OR a
natural-language string ("6 in", "180cm", "45°", "1.57rad"), canonicalized to
the unit the handler already expects (meters for length, radians/degrees for
angles) with min/max bounds and model-readable errors. Makes LLM tool calls
safer — "6 in" no longer has to be pre-converted to 0.1524, and a bad value is
rejected with a message the model can self-correct from.

A shared `measurement(kind, unit)` zod field wraps lingo's parseQuantity as a
`number | string` union+transform; numbers pass through unchanged (backward
compatible), so no handler changes were needed. Covers create_wall, cut_opening,
place_item, create_level, create_story_shell, create_roof,
create_stair_between_levels, create_room, add_door, add_window, photo_to_scene.

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

packages/mcp/src/tools/photo-to-scene/photo-to-scene.ts

@@ -13,6 +13,7 @@ import {
 import { z } from 'zod'
 import type { SceneOperations } from '../../operations'
 import { appendLiveSceneEvent } from '../live-sync'
+import { measurement } from '../measurement'
 
 /**
  * Input shape for the `photo_to_scene` orchestrator. `image` matches the
@@ -23,8 +24,14 @@ export const photoToSceneInput = {
   scaleHint: z.string().optional().describe('e.g. "1 cm = 1 m" or "approx 80 m²"'),
   name: z.string().default('Scene from photo'),
   save: z.boolean().default(true),
-  defaultWallThickness: z.number().default(0.2),
-  defaultWallHeight: z.number().default(2.6),
+  defaultWallThickness: measurement('length', 'm', {
+    min: 0,
+    description: 'Default wall thickness.',
+  }).default(0.2),
+  defaultWallHeight: measurement('length', 'm', {
+    min: 0,
+    description: 'Default wall height.',
+  }).default(2.6),
 }
 
 export const photoToSceneOutput = {