docs(cli,ledger): sweep #159 demo-retirement drift — stale comments + ledger notes

Cycle-close audit tidy for the #159 demo-retirement arc: behaviour-free
reword of prose/comments/docs left pointing at symbols the arc deleted.
Adversarially verified by the audit workflow; cargo build --workspace
--all-targets green.

- README: drop the removed `--harness` token; restrict the legacy built-in
  form claim to walkforward/mc/generalize (run/sweep no longer resolve one).
- glossary: the built-in `--strategy` sweep surface is retired (#159), not a
  live inline path.
- INDEX.md ledger: append [HISTORY] supersession markers (house style) to the
  dated realization notes advertising the retired `--harness` / built-in
  `--strategy` CLI forms (cost-flag #153, cycles 0065/0066/0067, name-res,
  #210 status); historical text preserved.
- aura-engine test-fixture docs: drop dead cross-crate refs to the deleted
  aura-cli fns sample_harness / build_sample and the deleted `macd` composite.
- cli_run.rs: reword the #159-cut-2 pin doc to the current clap generic-usage
  reality (no strategy_from / Strategy::RBreakout); r_sma_sweep_family ->
  blueprint_sweep_family.
- verb_sugar.rs: fix the pre-existing `E[R]` unresolved-doc-link warning.

Remaining tidy — the main.rs comment cluster plus its rustdoc link at :1546
(the second cargo-doc warning) — held for a follow-up issue. The dead
cost-graph branch is tracked in #221. refs #159

crates/aura-engine/src/graph_model.rs

@@ -333,8 +333,7 @@ mod tests {
     /// source role (`price`, → a synthetic source node), a composite reference
     /// (`sma_cross`, → a `composites` entry), a plain node (`Bias`), and a
     /// sink (`Recorder`, `output: vec![]`). A deliberately minimal serializer
-    /// fixture, independent of the CLI's built-in sample (`build_sample` in
-    /// aura-cli — a richer nested `signals` graph since cycle 0036), kept small so
+    /// fixture, kept small so
     /// this golden stays stable; the Recorder receiver is dropped because the
     /// model serializer never runs the graph.
     fn sample_root() -> Composite {