fix(aura-cli): sweep --list-axes joins the gated intake class

Fieldtest finding B1: the one remaining authored-envelope FILE route,
sweep --list-axes, skipped the root-name gate — a hand-edited
"name":"../escape" listed mangled, non-bindable wrapped axis names
at exit 0 while every sibling intake refused. The discovery surface now
gates before any axis line prints (exit 1, shared prose), restoring
both the #331 every-authored-intake claim and #328's discovery-surface
identity. RED-first: the e2e refusal test was written and observed
failing (exit 0, axis lines printed) before the fix.

Re-enumeration of every read_to_string-fed envelope load confirms the
class is now closed; C24 additionally ratifies the fieldtest's SG1 —
the refusal core sentence is byte-uniform across sites while the
leading context prefix varies by site convention.

refs #331, #328

docs/design/contracts/c24-blueprint-data.md

@@ -205,11 +205,16 @@ replayed in order; nodes are referenced **by identifier**, ports as dotted
   `..`) applied at this op intake **plus every CLI intake that reads an
   authored blueprint envelope from a file** — `register`, `introspect
   --content-id <FILE>`, the bare graph-file viewer, `run`, `introspect
-  --params <FILE>`, and each of `sweep`/`walkforward`/`mc`/`generalize`'s
-  file-reading entry points (synthetic and `--real` alike) — one class of
-  intake, one gate. Store read-back (`reproduce`, `use` resolution,
-  `introspect`/`--params` by content id) stays deliberately ungated — C29: a
-  registered artifact is never retroactively invalidated.
+  --params <FILE>`, `sweep --list-axes`, and each of
+  `sweep`/`walkforward`/`mc`/`generalize`'s file-reading entry points
+  (synthetic and `--real` alike) — one class of intake, one gate. The
+  refusal's core sentence (`name_gate_fault_prose`) is byte-uniform across
+  every one of these sites; only the leading context prefix varies —
+  `run` and the bare graph-file viewer prepend `aura: <path>:`, while
+  `register`, the sweep-axis family (`validate_and_register_axes`), and
+  `introspect` prepend bare `aura: `. Store read-back (`reproduce`, `use`
+  resolution, `introspect`/`--params` by content id) stays deliberately
+  ungated — C29: a registered artifact is never retroactively invalidated.
 - `source` — `{"op":"source","role":<str>,"kind":<ScalarKind>}` — declare a root
   source role producing a base column of `kind`.
 - `input` — `{"op":"input","role":<str>}` — declare a root input role (kind inferred