[wieslawsoltes]

Problem

The exact Linux package gate crashes across otherwise independent V8 executables while v8_dom_runtime::implementation is destroyed. The captured GDB stack enters GlobalHandles::NodeSpace::Release after the owned isolate has already been disposed.

Change

Release every previously omitted persistent-handle owner before Isolate::Dispose():

• generated meter, output, and progress element templates;
• active drag transfer wrappers;
• active outbound drag transfer wrapper;
• discrete wheel animation context.

This completes the destructor's existing explicit lifetime boundary. It adds no steady-state work or storage.

Validation

• Audited every direct v8::Global member and nested runtime-state owner against the destructor.
• git diff --check passes.
• The cumulative exact package gate on the top of the stack will validate owned/shared isolate teardown on Linux and Windows.

Fixes #851