iter design-md-rolesplit.1 (DONE 9/9): DESIGN.md -> design/ ledger role-split

The 3020-line docs/DESIGN.md is replaced by the design/ ledger:
design/INDEX.md (sole addressable spine, typed Contracts+Models tables,
polymorphic links — prose file OR authoritative source //!), 14
design/contracts/*.md test-linked invariants + 3 source-link-only
contracts (mangling/env-construction/qualified-xref, no prose file —
code is SoT), 5 design/models/*.md whitepapers, and
docs/journals/2026-05-19-design-decision-records.md (the
relitigation-guard archive — every why/rejected/does-not-do/rollback/
empirical ### moved out at ###-granularity). Clean cut: git rm
docs/DESIGN.md, no stub.

RED-first crates/ailang-core/tests/design_index_pin.rs — the 4-clause
anti-regrowth spine (DESIGN.md-gone / every-INDEX-link-resolves /
every-contract-names-a-resolvable-ratifier /
contracts-carry-no-decision-record-prose) — demonstrably RED before,
GREEN after. Build-atomic by task ordering: design_schema_drift.rs's
include_str! (the only compile-time consumer) retargeted to
design/contracts/data-model.md BEFORE the deletion; its
## Data model/## Pipeline slicer dropped (a simplification the split
enables). 2 NoInstance diagnostics + 2 lockstep E2Es retargeted to
design/contracts/{float-semantics,typeclasses}.md. ~12 agent reading
lists + 5 SKILL bodies + CLAUDE.md + skills/README.md + ~25
code/C/.ail/spec comment xrefs retargeted; OQ7 dangling 'Iter 13b'
cite deleted (no forward target — a pointer would be fiction).
honesty-rule.md rewritten so the rule names the new home
(rationale->journals), resolving the recon-found internal
contradiction; the two docs_honesty_pin.rs:70,72 pinned phrases kept
verbatim+contiguous.

Boss-verified independently: cargo test --workspace 646 passed /
0 failed; design_index_pin 4/4; acceptance grep CLEAN of live
DESIGN.md refs (residuals = only the spec-mandated clause-4
deletion-enforcer). 2 DONE_WITH_CONCERNS routed to the mandatory
milestone-close audit: (a) str-abi.md:23 '(iter str-concat,
2026-05-13)' provenance stamp trips advisory architect_sweeps Sweep-1
— Boss-confirmed byte-identical to DESIGN.md@deeffb1:2062-2065, a
faithfully-migrated PRE-EXISTING anchor (regexes verbatim, only path
retargeted), NOT split-introduced — RATIFY-or-tidy at audit; (b) a
now stale-direction intra-prose 'see Str ABI below' cross-ref in
float-semantics.md — audit-adjudication candidate. Plan defect noted:
Task 9 Step 4's verbatim acceptance grep used a ^./ anchor not
matching the system's grep -rIn output; substance re-verified CLEAN.

Spec grounding-check PASS x2. Journals INDEX + decision-records
pointer appended (Boss-only).

crates/ailang-surface/src/lib.rs

@@ -4,7 +4,7 @@
 //! [`ailang_core::ast::Module`] values. The JSON-AST in `ailang-core`
 //! remains the canonical, hashable, content-addressed source of truth;
 //! form (A) is the AI-authoring projection optimised for token-efficient
-//! production by LLMs (see `docs/DESIGN.md` Decision 6).
+//! production by LLMs (see `design/contracts/authoring-surface.md`).
 //!
 //! ## Modules
 //!

crates/ailang-surface/src/parse.rs

@@ -75,10 +75,12 @@
 //! lit-form ::= integer | "true" | "false" | string
 //! ```
 //!
-//! Notes on the form (deviations from the spec in DESIGN.md Decision 6):
+//! Notes on the form (the binding constraints are in
+//! design/contracts/authoring-surface.md; the form-refinement
+//! rationale is in docs/journals/2026-05-19-design-decision-records.md):
 //!
 //! - The `lam` form carries `paramTypes`, a `ret` type, and an
-//!   optional `effects` clause. The original DESIGN.md sketch left
+//!   optional `effects` clause. The early form sketch left
 //!   these out; the AST stores them per-lambda and so the form must
 //!   round-trip them.
 //! - The `import` form admits an optional `as` alias to round-trip

crates/ailang-surface/src/print.rs

@@ -125,7 +125,7 @@ fn write_type_def(out: &mut String, td: &TypeDef, level: usize) {
     }
     // Iter 18e: `(drop-iterative)` annotation. Printed last (after
     // every ctor) so the canonical form lands consistent with the
-    // DESIGN.md example. Omitted when `drop_iterative == false`.
+    // design/contracts/data-model.md example. Omitted when `drop_iterative == false`.
     if td.drop_iterative {
         out.push('\n');
         indent(out, level + 1);