Self-host: AOT link for `new` and user-defined functions (JIT __object__)

[PurHur]

Problem

Bootstrap Phase B lint passes for test/bootstrap-aot/minimal_class.php and nullable_types.php, but Phase C link fails:

• minimal_class.php uses new Greeter() → JIT: Unsupported native type __object__
• nullable_types.php uses user-defined greet() → compile/link not ready

These are excluded from aot_link_targets in bootstrap-lib.php until fixed.

Tasks

• Register / enable __object__ JIT type (lib/JIT/Builtin/Type/Object_.php is currently commented out)
• AOT link minimal_class.php and class_nullable_property.php
• AOT link nullable_types.php (namespaced or plain user func)
• Remove entries from bootstrapDefaultAotLinkTargets() link-pending list

Tracks #212 / #512.

[PurHur]

Progress from subagent work (merged to master):

• Enable AOT link for bootstrap class fixtures (__object__ JIT) #523 — __object__ JIT type + new/method lowering; minimal_class.php links and runs.
• AOT lint: lower class Const_ for lib/OpCode.php (#84) #522 — Const_ lowering for AOT lint; lib/OpCode.php -l passes.
• Fix AOT nullable property on instance methods (#520) #524 — $this as method param, nullable property fetch/===, class_nullable_property.php in link targets.

Still lint-only: nullable_types.php (user func), class_constants.php (no JIT DECLARE_CLASS_CONST yet).