docs(hpc): mark l1/l2/linf as materialised (wave-2 update prepended)

Addresses PP-13 HOLD finding: docs/hpc-stability.md framed
l1_f64_simd/l2_f64_simd/linf_f64_simd as "aspirational reserved
names" because they were absent from source at wave-1 time. Wave-2
commit 71cdbd4 materialised all three; the doc now opens with a
prepended status block stating the freeze commitment is load-bearing,
not aspirational. The "Stable public surface" table below the
banner now describes REAL APIs.

Per PP-13 savant audit. Wave-3 of the four-repo integration.

Author: claude

docs/hpc-stability.md

@@ -1,5 +1,17 @@
 # HPC API Stability Commitment — AdaWorldAPI/ndarray Fork
 
+> **2026-05-18 wave-2 update**: `l1_f64_simd`, `l2_f64_simd`, and
+> `linf_f64_simd` were initially marked as "aspirational reserved names"
+> in this doc because they were absent from the source at wave-1 time
+> (per `docs/hpc-api-inventory.md`). Wave-2 commit `71cdbd4`
+> ("feat(hpc): materialise l1_f64_simd, l2_f64_simd, linf_f64_simd in
+> heel_f64x8") materialised all three with the exact signatures this doc
+> promised, matching `cosine_f64_simd`'s F64x8-chunk + scalar-tail
+> pattern. 15/15 `heel_f64x8` tests pass. The "Stable public surface"
+> table below now describes REAL APIs — not promises. Reading order:
+> the freeze commitment is now load-bearing, not aspirational.
+
+
 **Status:** DRAFT — first published 2026-05-18
 **Branch at time of publication:** `claude/lance-surrealdb-analysis-LXmug`
 **Applies to crate:** `ndarray` v0.17.x (AdaWorldAPI fork of rust-ndarray/ndarray)