iter pd.2: surface owns prelude embed; pd.1 shim retired

Moved PRELUDE_AIL const + parse_prelude fn to ailang-surface;
re-exported from surface's lib.rs. surface::load_workspace rewritten
3-line shim-call → 7-line composition: load_modules_with → reserved-name
check → inject parse_prelude → build_workspace(&["prelude"]).

Five deletions in core: PRELUDE_JSON, load_prelude, load_workspace_with
(the pd.1 shim), the top-level cfg(test) load_one fn, and the
cfg(test) crate::load_module import. Production literal-"prelude" count
in crates/ailang-core/src/ is now zero. Cross-form-identity preflight
PASSED at module_hash 3abe0d3fa3c11c99 — parse(prelude.ail) ≡
deserialize(prelude.ail.json), so pd.3's deletion of the JSON is safe.

Three new pin tests in ailang-surface/tests/: prelude_parse_pin (succeeds
+ min defs); prelude_module_hash_pin (cross-form-identity + literal-hex
anchor); prelude_injection_pin (inject + reservation).

Plan deviations (recorded in journal): switched the regression-pin
fixture from non-existent examples/hello.ail.json to hello.ail; relocated
10 in-mod core tests to crates/ailang-core/tests/workspace_pin.rs
because the dev-dep cycle (core ↔ surface) prevents in-mod aliasing in
the lib-test target (form-a.1 T5 precedent); preserved load_one
production-symbol-deletion by adding a test-mod-private load_one helper
in core's mod tests for the 2 pd.1-introduced tests still consuming it.

cargo test --workspace 573 green (+9 net from pd.1 baseline).
bench/cross_lang.py + bench/compile_check.py exit 0; bench/check.py
exit 1 with established noise envelope (bench_list_sum.bump_s, 13th
consecutive observation; pd.2 is workspace-loader-only, no codegen
touch — baseline pristine).

bench/orchestrator-stats/2026-05-14-iter-pd.2.json

@@ -0,0 +1,19 @@
+{
+  "iter_id": "pd.2",
+  "date": "2026-05-14",
+  "mode": "standard",
+  "outcome": "DONE",
+  "tasks_total": 6,
+  "tasks_completed": 6,
+  "reloops_per_task": {
+    "1": 0,
+    "2": 0,
+    "3": 0,
+    "4": 0,
+    "5": 0,
+    "6": 0
+  },
+  "review_loops_spec": 0,
+  "review_loops_quality": 0,
+  "blocked_reason": null
+}