feat: multi-format 3D viewer with large-file OBJ streaming, Z-up, projection/outline UI

Three.js viewer supporting glb/gltf/obj/fbx/dae/ifc/ply via both server (SSR)
and drag&drop (CSR) paths.

- Streaming OBJ parser (src/viewer/objStream.ts) for files past the V8 max
  string length (>~1GB text) that OBJLoader can't handle; indexed geometry,
  per-vertex color from MTL Kd, float64 recenter baked in.
- In-viewer float64 recenter (objRecenter.ts) for huge CAD/survey coordinates
  (~1e8) so float32 vertex buffers keep precision (no cracked faces).
- Z-up right-handed world; Y-up formats rotated on load.
- OBJ+MTL+texture drag&drop (LoadingManager URL-modifier maps dropped images).
- OrbitControls ground-plane panning (road/rail alignment workflow).
- UI: Zoom Fit, perspective/orthographic toggle, feature-edge outline.
- DoubleSide for CAD OBJ; PLY mesh + point-cloud support.

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

.claude/commands/bootstrap.md

@@ -0,0 +1,13 @@
+---
+description: Bootstrap the hmwebviewer project from the architecture spec (Phase 0). Run once when PLAN.md is not started.
+---
+
+Read `CLAUDE.md`, `PLAN.md`, `3d_viewer_architecture_spec.pdf` (extract via `pdftotext -layout`), then execute Phase 0 of PLAN.md:
+
+1. Scaffold Vite + TypeScript project. Install `three` + `@types/three`.
+2. Place Draco + KTX2 decoder assets under `public/draco` and `public/basis` (or wire CDN fallback). Pin to the installed three.js version.
+3. Create a minimal `src/viewer/ThreeDViewer.ts` with a WebGLRenderer scene (camera, lights, resize loop) rendering a test cube.
+
+Verify each step with real output: `npm run dev` serves, `npm run build` exits 0, console clean. Update PLAN.md (P0-* → done) and append to PROGRESS.md.
+
+Arguments: $ARGUMENTS (optional override, e.g. package manager `pnpm`/`npm`).