refactor: extract the member-run recipe into library crates (#295 part 1)

The shell no longer defines what an aura backtest is. Tasks 1-9 of the
shell-boundary cycle — structural extraction, behaviour byte-identical:

- aura-runner (new; the C28 assembly position): input binding (the C26
  module, moved whole), the C1-load-bearing param<->config translators,
  harness assembly (wrap_r / run_signal_r / run_blueprint_member and the
  probe/reopen cluster), axis + risk-regime conventions (bind_axes et
  al.), the campaign family builders + MC guards, reproduce
  (process::exit -> RunnerError, shell remaps to identical bytes), the
  measurement-run orchestration, project loading (Env / cdylib load /
  charter / staleness, moved whole), the coverage gap-walk (deduplicated
  onto interior_gap_months), and DefaultMemberRunner — the public
  implementation of aura_campaign::MemberRunner (ex CliMemberRunner).
  The MemberRunner trait stays in aura-campaign; the column still
  imports no harness/data-binding machinery.
- aura-measurement (new; seeds C28 rung 3): the IcMetrics/IcKey
  vocabulary + information_coefficient, verbatim incl. serde derives
  (#294 duplicate-timestamp semantics move as-is, unresolved).
- aura-backtest: the pure per-run scaffold (point_from_params,
  wf_ms_sizes / fit_wf_ms_sizes, intersect_shared_window).
- shell residue: main.rs / campaign_run.rs keep argv/dispatch,
  argv->document translation, and presentation only;
  walkforward_summary_json_from_reports now calls the public
  aura_engine::param_stability instead of its inline twin.
- worked example (crates/aura-runner/examples/world_member_run.rs): a
  World program runs a member backtest through the library alone.

Held quality findings, adjudicated: the plan's literal pub-visibility
list for binding.rs kept (cosmetic); ~20 refusal sites inside
aura-runner (family/member/measure/translate) still process::exit —
behaviour-identical today, conversion to RunnerError is filed forward
(refs #297); rustfmt line-width drift on re-pathed call sites left for
a repo-wide fmt decision.

Verification: cargo test --workspace green (1471 passed, 0 failed);
cargo clippy --workspace --all-targets -D warnings clean. Byte-identity
is pinned by the untouched shell E2E suites (cli_run, measure_ic,
run_measurement, research_docs, run_refuses_unrunnable_blueprint,
tap_recording — zero assertion edits).

Remaining in this cycle: full-workspace c28_layering + shell-content
check, ledger amendments (C28 assembly position, C25/C14 control-surface
consequence, C26 realization note).

refs #295

crates/aura-vocabulary/tests/c28_layering.rs

@@ -36,6 +36,7 @@ fn node_crates_obey_the_c28_import_direction() {
     // (crate, the intra-workspace [dependencies] C28 permits for its layer)
     let allowed: &[(&str, &[&str])] = &[
         ("aura-analysis", &[]),                          // foundation: no aura-* deps
+        ("aura-measurement", &["aura-core", "aura-analysis"]),
         ("aura-std", &["aura-core"]),
         ("aura-market", &["aura-core"]),
         ("aura-strategy", &["aura-core"]),