iter raw-buf.4 rawbuf-payload-termnew-desugar (DONE, drop-call deferred to .5): RawBuf works, prints 60 (refs #7)

Ships RawBuf end-to-end as a consumer of the raw-buf.3 scope-qualified
intrinsic mechanism, plus the general Term::New construction sugar.
Working subset committed; the drop-CALL ratification (no-leak) is
re-carved to raw-buf.5 (see b49f57d) — the flat drop FUNCTION ships here,
its call-insertion needs a codegen resolution mechanism.

What ships (all green):
- raw_buf kernel-tier submodule (crates/ailang-kernel/src/raw_buf/):
  RawBuf TypeDef (param-in {Int,Float,Bool}, ctor B a) + four
  (intrinsic) ops new/get/set/size. parse_raw_buf + workspace injection
  (kernel-tier auto-imported); workspace count 4 -> 5.
- 12 scope-qualified INTERCEPTS entries RawBuf_{new,get,set,size}__{Int,
  Float,Bool} + emit fns: new allocs an @ailang_rc_alloc slab
  (8-byte i64 size header + n*width element bytes), get/set
  getelementptr+load/store at offset 8 + i*width, size loads the header.
  Mechanical on the raw-buf.3 naming + bijection machinery; bijection
  green (4 markers -> 12 entries).
- Term::New desugar (crates/ailang-core/src/desugar.rs): (new T <types>
  <values>) -> (app T.new <values>), runs before check so the
  type-scoped callee flows through the raw-buf.3 scope threading to
  RawBuf_new__T; drops the NewArg::Type (element type inferred from
  use). Both codegen Term::New deferral arms removed (replaced with
  unreachable!). Ratified by new_stubt_builds_and_runs.
- Flat intrinsic-storage drop FUNCTION @drop_raw_buf_RawBuf (single
  @ailang_rc_dec on the slab), emitted for any TypeDef whose new op is
  (intrinsic)-bodied — distinguishes RawBuf (intrinsic new) from StubT
  (real-body new -> generic ADT drop).
- E2E: raw_buf_int (-> 60), raw_buf_float (-> 4.0), raw_buf_bool
  (-> 42), raw_buf_param_in_reject (param-not-in-restricted-set).

In-scope additions beyond the literal plan (both sound, ratified):
- qualify_workspace_term now normalises a monomorphic cross-module
  type-scoped callee (StubT.new) to <home>.f; without it
  new_stubt_builds_and_runs cannot build (StubT.new is monomorphic, so
  the raw-buf.3 poly-mono path mints no symbol). Same-module + polymorphic
  callees carved out.
- diagnostic-behaviour: (new T ..) missing-new-op now surfaces
  type-scoped-member-not-found (desugar runs before check, bypassing
  synth's Term::New arm); new-arg-kind-mismatch obsoleted. Two unit
  tests updated to the new behaviour. param-in reject unaffected.

The 5 .ll snapshots gained @drop_raw_buf_RawBuf (+ partial) — injecting
raw_buf emits its drop fn into every program; benign, regenerated to the
final IR. (The plan's "snapshots stay green" assumption was wrong.)

Verification (orchestrator, this session): cargo test --workspace 676
passed / 0 failed / 2 ignored. raw_buf_int_e2e prints 60; bijection,
round-trip, new_stubt, float/bool/reject all green. The raw_buf_no_leak
test is NOT in this commit — it moves to raw-buf.5 with the drop-call
resolution that makes it pass (the slab currently leaks at scope close;
tracked, fixed next iter; milestone not released until close).

examples/raw_buf_bool.ail

@@ -0,0 +1,10 @@
+(module raw_buf_bool
+  (fn main
+    (doc "raw-buf.4 Bool variant: store true in a 1-slot Bool RawBuf, read it back, discriminate to an Int and print (42). Exercises RawBuf.new/.set/.get @ Bool (i1 load/store, width-1 offsets).")
+    (type (fn-type (params) (ret (con Unit)) (effects IO)))
+    (params)
+    (body
+      (app print
+        (let buf (new RawBuf (con Bool) 1)
+          (let buf (app RawBuf.set buf 0 true)
+            (if (app RawBuf.get buf 0) 42 0)))))))