fix(runtime): Object.defineProperty on Class.prototype (drizzle applyMixins) — #2159

[proggeramlug]

Summary

Closes #2159 — Object.defineProperty(C.prototype, name, descriptor) is now
honored on a class-ref receiver, so the applyMixins(Target, [Source])
pattern works and drizzle-orm's await db.select().from(users) resolves
through the inherited QueryPromise.then thenable.

Class.prototype evaluates to the class-ref itself in Perry (not a
separate prototype object — see the existing class_ref_id arm in
js_object_get_own_property_descriptor). Pre-fix the defineProperty
runtime helper hit extract_obj_ptr → null on that class-ref and silently
dropped the descriptor, so (new C()).method came back undefined.

The fix detects the class-ref receiver up front and installs the
descriptor's value where instance lookup will find it:

• BOUND_METHOD_FUNC_PTR closures (what getOwnPropertyDescriptor
  returns for class methods, hot path for applyMixins): extract the
  source class-ref + method name from the closure's captures, look the
  method up in the source class's vtable chain via the existing
  lookup_class_method_in_chain, and copy the raw (func_ptr, param_count) entry onto the target class's CLASS_VTABLE_REGISTRY.
  Dispatching the bound closure directly would route through
  js_native_call_method on the source class-ref (static-dispatch arm)
  and never reach the inherited instance method.
• Other callables (user-supplied { value: function (…) { … } }):
  route through js_register_prototype_method — the same
  Class.prototype.m = fn direct-assignment side table that
  lookup_prototype_method already consults on the instance-lookup miss
  path.

Test plan

• New gap test test_gap_2159_defineproperty_class_prototype.ts
  pins the single-method install + full applyMixins shape + the
  await thenable assimilation. Byte-identical with
  node --experimental-strip-types.
• tests/release/packages/drizzle-mysql/entry.ts switched from the
  explicit-.execute() workaround to idiomatic
  await db.select().from(users) form. Fixture passes (with MySQL
  running on 127.0.0.1; CI wiring is compat: Drizzle + MySQL end-to-end CI job #804).
• cargo test --release -p perry-runtime --lib — 735/735 pass.
• cargo fmt --all -- --check clean.

Related

• Closes drizzle MySqlSelectBase: inherited .then resolves to undefined under Perry (await returns the builder) #2159
• Closes the .execute() workaround in Drizzle: 50-line program against real MySQL via @perry/mysql (followup to #488) #489 (drizzle-mysql fixture).
• Builds on await thenable returns the thenable itself instead of calling .then(resolve, reject) #586 (js_assimilate_thenable — already in place; this fix
  is what makes lookup_class_method_in_chain actually find the
  inherited then).