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/settings.json

@@ -0,0 +1,36 @@
+{
+  "permissions": {
+    "allow": [
+      "Edit(/.claude/skills/modeler-architecture/**)",
+      "Edit(/.claude/skills/license-gate/**)",
+      "Edit(/.claude/skills/feature-recipe/**)",
+      "Edit(/.claude/skills/topo-naming/**)"
+    ]
+  },
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "startup|resume|clear",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash .claude/hooks/session-start.sh",
+            "timeout": 10
+          }
+        ]
+      }
+    ],
+    "PreToolUse": [
+      {
+        "matcher": "Edit|Write",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash .claude/hooks/license-guard.sh",
+            "timeout": 10
+          }
+        ]
+      }
+    ]
+  }
+}