fix(registry,cli): chart resolves the depth-2 sweep --trace family layout

TraceStore::name_kind and read_family resolved taps exactly one
directory below the family handle, so the per-member fan-out layout
sweep/walkforward --trace writes since #224
(<name>/<cell>/<member>/index.json) classified as NotFound and
`aura chart <printed handle>` exited 1. Both sides now resolve depth-1
(campaign nominee layout) and depth-2, with depth-2 members keyed
<cell>/<member> (deterministic sort, C1); the on-disk layout is
unchanged. emit_chart's not-found message no longer suggests re-running
with the unknown handle as --trace (the data-creating command cannot
take an output handle as input); the message prefix stays pinned.
Milestone-fieldtest finding B1 (fixtures: 09da04f); verified against
the fieldtest's own on-disk family and the campaign depth-1 sibling.

crates/aura-cli/src/main.rs

@@ -444,8 +444,8 @@ fn emit_chart(name: &str, tap: Option<&str>, mode: ChartMode, env: &project::Env
         NameKind::NotFound => {
             eprintln!(
                 "aura: no recorded run or family '{name}' under runs/traces \
-                 (run `aura sweep --real <SYM> --trace {name}` or \
-                 `aura walkforward --real <SYM> --trace {name}` first)"
+                 (check the handle a sweep/walk-forward/campaign run printed for a typo — \
+                 re-running with this handle as `--trace` will not create it)"
             );
             std::process::exit(1);
         }