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)

scripts/build-apk.mjs

@@ -99,7 +99,7 @@ const kotlinStdlib = fs
 if (!kotlinStdlib) throw new Error('kotlin-stdlib not found in Gradle lib')
 
 const appVersion = JSON.parse(fs.readFileSync(path.join(root, 'package.json'), 'utf8')).version
-const versionCode = Number(process.env.APP_VERSION_CODE || 7)
+const versionCode = Number(process.env.APP_VERSION_CODE || 8)
 
 const env = {
   ...process.env,