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/hooks/progress-nudge.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# PostToolUse hook (Edit|Write) — nudge to update PROGRESS.md when runtime code changes.
+# Reads the tool call JSON from stdin; if the touched file is under src/ or tools/,
+# emit a one-line reminder. Non-zero/empty output otherwise.
+input="$(cat)"
+path="$(printf '%s' "$input" | grep -o '"file_path"[[:space:]]*:[[:space:]]*"[^"]*"' | head -1 | sed 's/.*"file_path"[[:space:]]*:[[:space:]]*"//;s/"$//')"
+case "$path" in
+  *"/src/"*|*"/tools/"*)
+    echo "Edited runtime code ($path). If a PLAN.md task finished, run /report to update PROGRESS.md and flip its status."
+    ;;
+esac
+exit 0