# Add area diagnostics command

## Goal

Add a fast area diagnostics CLI for OSM structure and existing output artifact health.

## Requirements

- Add a fast diagnostics CLI for an area config.
- The command must not invoke QGIS, Blender, Cesium, or GLB compression.
- The report must scan the configured OSM XML for common manual-edit risks:
  bounds presence, nodes, ways, relations, building ways, building multipolygon
  relations, explicit heights, building levels, malformed relation members,
  unresolved member ways, open rings, and basic vegetation counts.
- The report must inspect existing output artifacts when present:
  GeoJSON directory, GeoPackage, QGIS project, `.blend`, render PNG, GLB,
  metadata, Cesium preview, compressed GLB, compressed metadata, and compressed
  preview.
- If a GLB exists, the report should reuse the existing GLB digest logic to
  summarize size, nodes, meshes, materials, images, accessors, and extensions.
- The command should emit clear warnings for likely trouble, including missing
  OSM bounds, malformed building multipolygons, missing expected artifacts, GLB
  over a conservative size budget, high node count, and high texture count.
- Add an npm script and README usage.

## Acceptance Criteria

- [x] `npm run diagnose:area -- --config config/areas/nantaizi-lake-innovation-valley.json`
      prints a useful text report without running heavy build stages.
- [x] The diagnostics report includes OSM structure, building relation health,
      vegetation counts, output artifact status, and GLB digest summary.
- [x] Missing optional output artifacts are warnings, not hard failures.
- [x] Syntax checks pass for the changed Node scripts.
- [x] README documents the new diagnostic command.

## Notes

- Keep `prd.md` focused on requirements, constraints, and acceptance criteria.
- Lightweight tasks can remain PRD-only.
- For complex tasks, add `design.md` for technical design and `implement.md` for execution planning before `task.py start`.