iter pd.3: prelude.ail.json retired — milestone prelude-decouple closed

Deleted examples/prelude.ail.json (-559 lines). The cross-form-identity
preflight test that ratified pd.3's load-bearing assumption at module
hash 3abe0d3fa3c11c99 has discharged its purpose and was removed
along with its supporting bytes; the long-term prelude_parse_yields_canonical_hash
anchor stays. The ail-CLI migrate-bare-cross-module-refs subcommand's
defensive include + lockstep skip-branch removed; the rewrite logic's
prelude-fallback capability silently retired with the synthetic insert
(known debt, doc-comment updated to reflect). One in-mod core test
relocated to crates/ailang-core/tests/workspace_pin.rs (pd.2.4 dev-dep
cycle precedent — in-mod call to ailang_surface still structurally
impossible).

carve_out_inventory.rs: 8 → 7 carve-outs, §C4(b) row dropped, header
sentence updated. form-a-default-authoring.md §C4(b) gets a "RETIRED
2026-05-14 by milestone prelude-decouple" status marker; original
historical text preserved. New prelude_decouple_carve_out_pin.rs
asserts examples/prelude.ail.json does NOT exist.

Milestone prelude-decouple closed: prelude exists on disk only as
examples/prelude.ail; ailang-core embeds zero prelude bytes; CLAUDE.md
"authors write .ail" doctrine holds without exception.

cargo test --workspace 573 green; bench/cross_lang.py +
bench/compile_check.py exit 0; bench/check.py exit 1 with the
established noise envelope (14th observation of bench_list_sum.bump_s
since audit-cma; pd.3 is filesystem + spec text + test deletion only,
no codegen / runtime / typecheck path edited — baseline pristine).

Folds in the orphan pd.2 INDEX entry that was left uncommitted in the
working tree.

docs/specs/2026-05-13-form-a-default-authoring.md

@@ -267,6 +267,15 @@ Justification per file:
   (changing the diagnostic) or refuse to encode at all (changing
   the test subject).
 
+> **Status: RETIRED 2026-05-14 by milestone prelude-decouple.** The
+> §C4 (b) compile-time-embed carve-out is empty post that milestone;
+> the prelude is now authored exclusively as `examples/prelude.ail`
+> and parsed at compile time via `ailang_surface::parse_prelude`. The
+> original §C4 (b) framing below is preserved as historical context;
+> it documents the doctrine inconsistency that prelude-decouple
+> resolved. See `docs/specs/2026-05-14-prelude-decouple.md` and the
+> per-iter journals 2026-05-14-iter-pd.{1,2,3}.md for the resolution.
+
 **(b) Compile-time-embed carve-outs (one file as of 2026-05-13):**
 
 ```