refactor(cli): retire the r-sma demo builder — topology now lives only as data (#159 cut 1b)

Cut 1b of the hard-wired demo retirement — the removal half. With the proven
example shipped in cut 1, delete the r-sma builder and its whole transitive
closure so no production function constructs the r-sma topology any more; it
exists only as data (crates/aura-cli/examples/r_sma{,_open}.json).

Deleted: sma_signal (the builder), r_sma_graph, run_r_sma (aura run --harness
r-sma), r_sma_sweep_family (aura sweep --strategy r-sma), the synthetic inline
r-sma walkforward/mc machinery (r_sma_space/r_sma_sweep_over/run_oos_r/
run_mc_r_bootstrap/mc_r_bootstrap_report + the walkforward_family RSma arm), both
fixture emitters, the round-trip + cut-1 byte-fidelity tests, the R_SMA_FAST/
SLOW/BIAS_SCALE consts, and the Strategy::RSma / HarnessKind::RSma / McArgs::RealR
variants. The three dissolved-verb synth sites (generalize/walkforward/mc
--strategy r-sma --real) now embed the shipped open example via include_str!
instead of building it — byte-safe, guarded by the unchanged dissolved-verb
real-archive goldens. The two now-redundant fixtures move to the examples
(deleted, ~40 readers repointed). The --cost-* flags on `aura run` retire with
the harness (their sole consumer was run_r_sma; cost-model coverage survives
engine/std/composites-level).

The retired demo surfaces (--harness r-sma, sweep/walkforward/mc --strategy r-sma
inline) have working data successors: aura run examples/r_sma.json, aura sweep
examples/r_sma_open.json --axis …, and the --strategy r-sma --real campaign path.

Deviation from the plan, noted: StopArm collapsed to StopRule in wrap_r's
signature (its only other variant, Open, died with r_sma_graph) — cleaner than
the planned vestigial single-variant enum; behaviour-preserving, touching
campaign_run.rs and the r-breakout/r-meanrev call sites.

Follow-up (not this cut): wrap_r's cost-node-building branch is now unreachable
(nothing passes Some(CostConfig) after run_r_sma's deletion) yet clippy-clean —
a latent cleanup for when the inline cost surface fully retires.

The stage1-r param-suffix remapping (r_sma_friendly_name + the FAST/SLOW/
STOP_LENGTH/STOP_K_SUFFIX consts) went dead and was removed, closing #167 by
deletion.

Verification (own, not the workflow's report): full `cargo test --workspace`
green; `cargo clippy --workspace --all-targets -- -D warnings` clean, no
dead-code residue; the cut-1 grade anchor (shipped_r_sma_example_reproduces_the_
builtin_grade) and the dissolved-verb real goldens (generalize/walkforward/mc
_dissolves_through_the_campaign_path) stay byte-identical. A first workflow
attempt was discarded after a subagent's `git checkout -- main.rs` recovery
silently reverted earlier tasks' edits (filed on the plugin tracker as
Brummel/Skills#23); this landing is the hardened re-run, verified by hand.

closes #167
refs #159

crates/aura-cli/src/campaign_run.rs

@@ -738,10 +738,10 @@ fn persist_campaign_traces(
             tx_ex,
             tx_r,
             tx_req,
-            crate::StopArm::Bound(aura_composites::StopRule::Vol {
+            aura_composites::StopRule::Vol {
                 length: crate::R_SMA_STOP_LENGTH,
                 k: crate::R_SMA_STOP_K,
-            }),
+            },
             false,
             None,
         )