docs(raw-buf): refresh fixture outcomes; ratify set non-enforcement (refs #7)

- rawbuf_1_score_table / rawbuf_2_running_max: the header OUTCOME blocks
  described the pre-fix breakage (does-not-check / unknown-variable).
  Those defects are fixed (B1 #46, B2 #47, B5); update the comments to
  the current state — both check, build, run to their expected values
  and are leak-clean under AILANG_RC_STATS. The files now serve as
  positive regression examples, not bug repros.

- design/models/0007 §RawBuf: ratify the fieldtest's B4 spec_gap. The
  `own -> own` signature of RawBuf.set is a threading discipline, not
  runtime-enforced single-use; a double-consume of the same owned buffer
  aliases one slab (consistent with every owned value in the language).
  State that single-use is the author's responsibility and full linear
  enforcement is Issue #22 territory.

Surfaced by the raw-buf fieldtest (docs/specs/0058).

examples/fieldtest/rawbuf_2_running_max.ail

@@ -11,12 +11,13 @@
 ;
 ; Expected stdout: 16  (slots 1,4,9,16; running max ends at 16).
 ;
-; OUTCOME: `ail check` passes ("ok"), but `ail build` FAILS at codegen:
-;   Error: module `rawbuf_2_running_max`: def `main`: unknown variable: `b`
-; The owned-RawBuf `loop` binder `b` threaded through `recur` is visible
-; to the checker but not to codegen. A plain Int loop binder named `b`
-; builds fine, so it is specific to threading an owned RawBuf value
-; through a loop binder. The check<->codegen agreement is broken here.
+; This was the fieldtest repro for B2 (#47): `ail check` passed but
+; `ail build` FAILED at codegen with `unknown variable: b` — the synth
+; type-replay walked the `loop` body without the loop binders in scope.
+; Now fixed: the replay descends through `loop` with its binders bound.
+; OUTCOME (current): checks, builds, runs; prints 16. Leak-clean under
+; AILANG_RC_STATS (the loop-threaded owned buffer drops at scope close,
+; B5 — the let-bound loop result is now registered for scope-close drop).
 
 (module rawbuf_2_running_max
   (fn main