Fix blank drawings, drop parse-time animation cost, add render diagnostics

Accuracy / completeness
- docViews: split parsed scene into model space / paper space / free-standing
  blocks (geometry hidden in uninserted blocks no longer shows as a blank
  canvas); auto-select the first block view when model space is empty
- viewer: view switcher panel listing every detected view with expanded
  entity counts; paper space is now parsed (includePaperSpace) and kept apart
- SHX: missing .shx references are surfaced with an import control
  (addReferenceFile), linetypes/text redraw afterwards
- unsupported/proxy entities: markers on canvas + diagnostics block showing
  proxy / wipeout counts and missing SHX names

Speed
- the loading overlay used an infinite CSS spinner + backdrop blur while the
  worker parsed; on software rendering that starved the parse thread
  (TELECOM 18MB: 71s -> 30s wall clock, normalize 33s -> 14s). Replaced with a
  determinate progress bar fed by loader progress events
- transferInputBuffer for worker loads, maxInsertDepth 32, longer worker timeout

Tooling
- scripts/probe-dwg.mjs / probe-app.mjs: headless render + end-to-end probes
  (entity/layer/block/layout/proxy stats, timings, screenshots)
- tools/render-probe.html, scripts/profile-worker.mjs
- version 0.6.0 (versionCode 8)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "phone-viewer-app",
   "private": true,
-  "version": "0.5.0",
+  "version": "0.6.0",
   "type": "module",
   "license": "AGPL-3.0-or-later",
   "description": "Mobile/tablet all-in-one viewer: DWG (model & layout space) + PDF/EPUB/XPS/CBZ/images",