audit: cycle-close tidy for the #256/#272 latecomer block

Drift review (architect) over a55e4cf..HEAD found the cycle substantially
clean — C25 closed vocabulary, C1 determinism/behaviour-preservation, the
additive-serde widening, exhaustive StageBlock matches, and the uniform exit-3
convention all hold. Two drift items resolved:

- RATIFY: the `SilencedPanic` member-boundary panic-hook silencer (added by the
  #272 implementer, not named in the spec) is a legitimate mechanism — it keeps
  "recorded, campaign continues" observably true on stderr by suppressing the
  default crash backtrace around each contained `catch_unwind`. Its mutex
  serialises only the ref-count/hook-swap (O(1)), never member computation, so
  C1 disjoint-parallel determinism is preserved. Documented in the ledger's
  #272 realization paragraph rather than left as undocumented global state.
- FIX: `cell_fault_kind_label` hand-wrote the snake_case strings that must match
  `CellFaultKind`'s serde `rename_all` (two sources of truth an aggregate over
  campaign_runs.jsonl could silently diverge from). Pinned with a test asserting
  each label equals the serialized form; the efficient `&'static str` stays.

(The #272 commit's own concern-driven doc fixes and the wf panic-containment
test landed in d3b1a1a; this commit carries only the two audit-phase items.)

Suite: cargo test --workspace green (1311 tests, 0 failed); clippy clean.

crates/aura-cli/src/campaign_run.rs

@@ -1564,6 +1564,24 @@ mod tests {
     /// bounds fall short of full coverage. GAPSYM-shaped input (files at
     /// 2024-01..02 and 2024-05..06, absent 03..04) over a Jan-through-June
     /// window must name exactly the two missing interior months.
+    /// #272: the summary label is a CHECKED mirror of the persisted serde form
+    /// — an aggregate over `campaign_runs.jsonl` counts by the serialized
+    /// `CellFaultKind` string, so the human-facing label must be exactly that
+    /// string (no second source of truth that could silently drift).
+    fn cell_fault_kind_label_matches_the_serialized_kind() {
+        use aura_registry::CellFaultKind as K;
+        for kind in [K::NoData, K::Bind, K::Run, K::Panic, K::Window] {
+            let serde_form = serde_json::to_string(&kind).expect("serialize kind");
+            let serde_form = serde_form.trim_matches('"');
+            assert_eq!(
+                cell_fault_kind_label(kind),
+                serde_form,
+                "the summary label must equal the persisted serde string"
+            );
+        }
+    }
+
+    #[test]
     fn interior_gap_months_names_a_whole_missing_month_spanned_by_the_window() {
         let months = [(2024u16, 1u8), (2024, 2), (2024, 5), (2024, 6)];
         // 2024-01-01T00:00:00Z .. 2024-07-01T00:00:00Z (Unix ms) — spans every