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/patches/cpython-3.13-webengine-unraisable.patch

@@ -0,0 +1,32 @@
+--- a/Python/errors.c
++++ b/Python/errors.c
+@@ -1584,6 +1584,15 @@
+ 
+    An exception must be set when calling this function. */
+ 
++#ifdef __EMSCRIPTEN__
++/* Optional native embedder notification, before allocation, exception
++ * normalization, audit hooks or sys.unraisablehook. The embedder must not call
++ * Python or retain the exception. Standalone CPython keeps its usual behavior.
++ * This also covers a deleted sys.unraisablehook and hook-argument OOM. */
++extern void web_engine_python_unraisable(const char *exception_type)
++    __attribute__((weak));
++#endif
++
+ static void
+ format_unraisable_v(const char *format, va_list va, PyObject *obj)
+ {
+@@ -1598,6 +1607,13 @@
+     PyObject *exc_type, *exc_value, *exc_tb;
+     _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+ 
++#ifdef __EMSCRIPTEN__
++    if (web_engine_python_unraisable != NULL) {
++        web_engine_python_unraisable(
++            exc_type != NULL && PyType_Check(exc_type)
++                ? ((PyTypeObject *)exc_type)->tp_name : NULL);
++    }
++#endif
+     assert(exc_type != NULL);
+ 
+     if (exc_type == NULL) {