Self-host M3: PHPTypes native unit probe (lib/PHPTypes subset) #2430

Problem

M3 unit probes cover Compiler (#2216), JIT (#2332), VM (#2354), and CFG parse (#2409) — but not the PHPTypes surface used on every compile path (\PHPTypes\Type, union/intersection constants, JIT external class seeds).

When native emit fails inside type coercion or Type:: constants, triage dumps into generic #2301 / #2323 buckets instead of a reproducible micro-probe.

Goal

1. test/selfhost/types_unit_probe/main.php — smallest require_once chain into vendor/ircmaxell/php-types / patched PHPTypes used by lib/Compiler.php
2. script/bootstrap-selfhost-types-unit-probe.sh — native AOT link + run; stdout contains types_unit_probe bundle OK
3. make bootstrap-selfhost-types-unit-probe + docs/bootstrap-selfhost.md M3 probes table row
4. Follow-ups: CI opt-in gate (mirror CI: BOOTSTRAP_PARSER_UNIT_PROBE_GATE opt-in in ci-local after #2409 #2417), north-star3-verify step (after Testing: north-star3-verify — add parser unit probe step after #2409 #2418), default-on flip

Implementation hints

Verification (local / Docker only)

make bootstrap-selfhost-types-unit-probe
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && make bootstrap-selfhost-types-unit-probe'

No GitHub Actions.

Acceptance criteria

• Probe script exists and passes on php-compiler:22.04-dev when LLVM 9 present
• Failure prints actionable hint (missing patch, unsupported type kind) — not bare segfault
• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 Phase 1 self-host lowering table references this probe

Dependencies

• Self-host M3: native compile-driver probe on lib/Compiler.php unit #2216 / Self-host M3: native compile unit probe on lib/Parser.php slice #2409 — sibling M3 probes (coordinate table in docs)
• M5: Prelink vendor (php-cfg, php-types, php-llvm) — no composer at cold boot #1416 — long-term vendor prelink (orthogonal)
• Language: Intersection types (A&B) in parameters and properties #1357 ✅ — intersection types on VM (reference)

Links

• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · Self-host M3: compile-driver real lowering symbol batch tracker #1768 compile-driver symbol batch tracker