Self-host M2: native-link 5 deferred spine inventory paths

[PurHur]

Problem

M2 spine smoke covers 606/611 inventory files with 5 deferred paths documented in script/check-selfhost-spine-coverage-sync.php ($spineNativeLinkDeferred):

• bin/vm.php
• lib/AOT/Linker.php
• src/llvm-env.php
• src/macro_functions.php
• src/yay-php8-compat.php

#2066 closed the 606→611 inventory regen; these five remain substitute/deferred and block honest bin/vm.php / linker paths in native self-host bundles.

Goal

Each deferred path either:

1. Lands as a real require_once in test/selfhost/compiler_lib_spine_smoke/main.php with native link green, or
2. Stays deferred with an updated documented reason in check-selfhost-spine-coverage-sync.php

Target: shrink $spineNativeLinkDeferred toward 0 before M5 (#1521).

Implementation hints

Path	Likely blocker	Tracker
lib/AOT/Linker.php	LLVM FFI / native link	#174 (toolchain), #1520 stubs
bin/vm.php	vm_run_smoke substitute under LLVM 9	#1846, #1867 VM smoke
src/llvm-env.php	env bootstrap in AOT	M3 #1768 symbol batches
src/macro_functions.php, src/yay-php8-compat.php	parser/macro edge	host #113

Probe after each batch:

BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke
php script/check-selfhost-spine-coverage-sync.php --verbose
docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev \
  make bootstrap-selfhost-lib-spine-smoke

Acceptance criteria

• At least one deferred path promoted to spine require_once with native link green on harness
• check-selfhost-spine-coverage-sync.php deferred table updated
• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 / Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 M2 row reflects new count

Links

• Self-host M2: Spine coverage gap — inventory 606→611 (regen drift) #2066 ✅ · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · Self-host M3: compile-driver real lowering symbol batch tracker #1768 M3 symbols · M2/M5: Retire PHP_COMPILER_SELFHOST_AOT stubs on Compiler compile spine #1520 stub retirement · 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78