iter hs.1: static-Str layout migration — packed-struct globals + sentinel rc-header + len

First iter of the heap-Str ABI milestone. Pure codegen refactor; every existing program produces byte-identical stdout.

Static-Str LLVM globals migrate from `[N x i8] c"…\00"` to `<{ i64, i64, [N x i8] }> <{ i64 -1, i64 N-1, [N x i8] c"…\00" }>`, carrying the UINT64_MAX sentinel rc-header (slot exploited in hs.2 via runtime short-circuit) and an explicit byte length. Two parallel intern paths (`intern_string` for raw format scaffolding, new `intern_str_literal` for language Str values) keep format strings untouched in `[N x i8]` shape.

IR-Str pointers now uniformly land on the len-field (offset +8 from rc-header, -8 from bytes). Four codegen sites that hand a Str pointer to a NUL-terminated-bytes C-API consumer now emit a +8 GEP first: `@puts` (io/print_str), `@ail_str_eq` (eq__Str intercept), `@ail_str_compare` (compare__Str intercept), and `@strcmp` (lower_eq Str arm — the 4th site was not in the plan; surfaced by Task-5 e2e regression and fixed inline).

6 new IR-shape pinning tests; `hello.ll` snapshot regenerated; cross_lang.py + compile_check.py + full `cargo test --workspace` green.

docs/journals/INDEX.md

@@ -30,3 +30,4 @@
 - 2026-05-12 — audit-ms: milestone close (Multi-subject Authoring-Form Test — CodeLlama Replication) — architect clean, bench all-green (same 5-metric latency.explicit_at_rc improvement cluster as audit-cma earlier today, baseline left pristine for second consecutive audit) → 2026-05-12-audit-ms.md
 - 2026-05-12 — iter ext-rename: `.ailx` → `.ail` extension rename across the live toolchain (61 example renames + 35 content edits + experiment-crate cohort rename `ailx → ail`); historical docs (journals, archive, specs, plans, frozen experiment runs) deliberately untouched; cargo+bench all-green; opens follow-up `.ail`-CLI-acceptance iter → 2026-05-12-iter-ext-rename.md
 - 2026-05-12 — iter ext-cli.1: `ail check`/build/run/...all 12 path-taking subcommands now accept `.ail` (Form A) inputs via `ailang_surface::{load_module, load_workspace}` (extension-dispatching loaders + injection point `core::load_workspace_with<F>`); workspace imports prefer `.ail` sibling over `.ail.json`; new `WorkspaceLoadError::SurfaceParse` variant routes surface parse errors as `surface-parse-error` structured diagnostics through `ail check --json`; DESIGN.md §Decision 6 CLI addendum; +7 new tests; closes the loop opened by iter ext-rename → 2026-05-12-iter-ext-cli.1.md
+- 2026-05-12 — iter hs.1: heap-Str ABI iter 1 — static-Str LLVM globals migrate from `[N x i8]` to packed-struct `<{ i64, i64, [N x i8] }>` carrying a `UINT64_MAX` sentinel rc-header + explicit `len`; IR-Str pointers now land on the `len`-field; `@puts` / `@ail_str_eq` / `@ail_str_compare` / `@strcmp` callsites GEP +8 to recover the bytes pointer (4 sites; plan listed 3, Task-5 e2e regression surfaced the 4th); 6 IR-shape pins; format strings stay raw `[N x i8]`; cross_lang.py + compile_check.py + full cargo test --workspace all green; byte-identical stdout across every example → 2026-05-12-iter-hs.1.md