chore: checkpoint web Blender migration source, tools and docs

Accumulated uncommitted work: GHOST Web backend, WebGL/GPU web layer,
web workflow engine and protocol, tooling, docs and task records.
Large generated evidence, user-testing archives, build snapshots and
imported test assets remain untracked.

Co-Authored-By: Claude Code <noreply@anthropic.com>

tools/web/check-autosave-edit-priority.mjs

@@ -0,0 +1,8 @@
+import assert from 'node:assert/strict'; import { AutosaveScheduler } from '../../web/app/src/storage/autosave.ts';
+const timers = new Map(); let serial = 0; globalThis.window = { setTimeout(callback) { timers.set(++serial, callback); return serial; }, clearTimeout(id) { timers.delete(id); } };
+const fire = async () => { for (const [id, callback] of [...timers]) { timers.delete(id); callback(); } await Promise.resolve(); };
+const deferred = () => { let release; const promise = new Promise(resolve => { release = resolve; }); return { promise, release }; };
+const scheduler = new AutosaveScheduler(), edit = deferred(); let entered = 0, commits = 0; scheduler.schedule(async isCurrent => { entered++; await edit.promise; if (isCurrent()) commits++; }, 1);
+await fire(); assert.equal(entered, 1); scheduler.cancel(); edit.release(); await scheduler.whenIdle(); assert.equal(commits, 0, 'new edit cancels waiting checkpoint');
+scheduler.schedule(() => { commits++; }, 1); await fire(); await scheduler.whenIdle(); assert.equal(commits, 1, 'recovery reschedules'); scheduler.schedule(() => { commits++; }, 1); scheduler.cancel(); await fire(); assert.equal(commits, 1, 'timer cancellation prevents dispatch');
+const write = deferred(); let writing = false, finished = false; scheduler.schedule(async () => { writing = true; await write.promise; finished = true; }, 1); await fire(); assert.equal(writing, true); scheduler.cancel(); assert.equal(finished, false); write.release(); await scheduler.whenIdle(); assert.equal(finished, true, 'active write retains ownership until finished'); scheduler.dispose(); console.log(JSON.stringify({status:'PASS',checks:['waiting callback cancellation','recovery reschedule','timer cancellation','active write completion']}));