iter intrinsic-bodies.2-migration-lock (DONE 4/4): prelude → (intrinsic) + bijection pin (refs #9)

Second and final iteration of the intrinsic-bodies milestone. Migrates
the 13 authored prelude dummy bodies to (intrinsic), rebaselines the two
hash pins that move, and locks the registry to the source with a
bijection. Behaviour-preserving: the codegen intercepts emit identical
IR; the prelude placeholder bodies were already dead (intercepted by
name before lower_term, since raw-buf.1).

What landed (4 tasks):

  Task 1 — examples/prelude.ail: 13 authored dummy bodies → (intrinsic).
    7 Eq/Ord instance methods (eq Int/Bool/Str/Unit, compare
    Int/Bool/Str) keep their lambda shell (params/ret = the method's
    local signature, Design X); the inner (body false)/(body true)/
    (body (term-ctor Ordering EQ)) becomes (intrinsic). 6 float_* fns
    ((body false) → (intrinsic) in the fn body slot). The honesty-rule
    infraction the milestone exists to fix is now closed: no prelude
    body lies about what runs.

  Task 2 — hash rebaselines (the prelude bytes changed):
    prelude module hash  af372f28c726f29f → 2ea61ef21ebc1913
    eq__Int       86ed4988438924d3 → cc7b99b63d1e44ae
    eq__Bool      d62d4d8c51f433f8 → fd0412f127986512
    eq__Str       3d32f377c66b03e0 → fa269285754a52da
    compare__Int  6d6c20520766368b → 0a02bd9effc9746c
    compare__Bool 02b64e8fadc913eb → d0dc108dacf4e543
    compare__Str  9645929d53cd3cc9 → d1419595dc52a456
    The 4 show__* mono pins did NOT move (Show bodies are real).

  Task 3 — intercepts.rs: registry_contains_all_legacy_arms (one-
    directional, hardcoded 18-name list) replaced by
    intercepts_bijection_with_intrinsic_markers. The in-source test
    walks prelude + kernel_stub pre-mono for Term::Intrinsic markers,
    recovers each marker's codegen symbol (mono_symbol(method, type) for
    instance methods; the fn name for top-level float_*/answer), and
    asserts a bijection over the intrinsic-backed class: (A) every
    marker resolves to an INTERCEPTS entry, (B) every INTERCEPTS entry
    not on the optimisation-only allowlist has a marker, plus a guard
    that the allowlist names are themselves registered. The allowlist is
    the 5 *__Int icmp-family entries, which intercept the monomorphised
    specialisation of the real-bodied polymorphic lt/le/gt/ge/ne — an
    optimisation, not a compiler-supplied body, so no marker. The pin
    passing independently confirms Task 1 missed no prelude site.

  Task 4 — confirmed no codegen path lowers an intercepted body (already
    true since raw-buf.1: try_emit_primitive_instance_body matches by
    name before f.body is inspected). Refreshed the now-accurate comment
    at lib.rs:1310-1319. design/contracts/0007-honesty-rule.md needed NO
    edit — it is a general present-tense rule and does not name the
    prelude dummies (confirmed by grep), so editing it would have been
    invented work.

Verification:
  cargo test --workspace → 669 passed, 0 failed (post-.1 baseline held;
    one test replaced net-0).
  Behaviour-preservation ratifiers GREEN (the safety net):
    eq_primitives_smoke_compiles_and_runs,
    compare_primitives_smoke_prints_1_2_3_thrice (e2e.rs);
    float_compare_smoke_prints_true_true_false (float_compare_smoke_e2e.rs);
    eq_ord_polymorphic_runs_end_to_end (eq_ord_e2e.rs).
  Bijection pin GREEN. Both hash pins GREEN at the new baselines.
  bench/check.py + compile_check.py → 0 regressed.

Plan-text imprecision (no outcome impact, noted for the record): Task 1
Step 5 wrote `--test e2e` for all four ratifiers, but
float_compare_smoke_prints_true_true_false and
eq_ord_polymorphic_runs_end_to_end live in their own test targets
(float_compare_smoke_e2e.rs, eq_ord_e2e.rs). The verification-filter
self-review checked that the fn names exist, not that they sit in the
named target — a sharper form of the filter-zero discipline. The
implementer ran each in its real target; all four green.

Milestone intrinsic-bodies is now feature-complete (.1 mechanism +
.2 migration+lock). Audit + close follow.

crates/ailang-codegen/src/lib.rs

@@ -1307,13 +1307,17 @@ impl<'a> Emitter<'a> {
         self.body.push_str(&sig);
         self.start_block("entry");
 
-        // primitive-instance body intercept. Returns true if
-        // the body was emitted in full (including the closing `}\n\n`).
-        // When that fires we skip the normal body-lowering block below
-        // but still fall through to deferred-thunk flush + closure-pair
-        // emission, so the intercepted fn participates in the same
-        // post-body machinery as every other top-level fn (iter 23.2.2
-        // fixup: previously this short-circuited past
+        // primitive-instance body intercept. Returns true if the body
+        // was emitted in full (including the closing `}\n\n`). A
+        // compiler-supplied body is an `(intrinsic)` marker
+        // (`Term::Intrinsic`) whose name resolves through the intercept
+        // registry — the intercept is matched by name here, before the
+        // body is ever inspected, so the marker is never lowered. When
+        // the intercept fires we skip the normal body-lowering block
+        // below but still fall through to deferred-thunk flush +
+        // closure-pair emission, so the intercepted fn participates in
+        // the same post-body machinery as every other top-level fn
+        // (iter 23.2.2 fixup: previously this short-circuited past
         // `emit_adapter_and_static_closure`, leaving the fn without a
         // closure-pair symbol — a footgun the moment any caller
         // referenced it by value).