feat(campaign): aura-campaign crate — types, member_metric, preflight (0107 tasks 4-5)

New leaf library crate: the campaign-execution semantics home (#198
home decision — reusable beyond the CLI; NOT C21's project-side
World). CellSpec + the MemberRunner seam (the only thing a consumer
implements), MemberFault/ExecFault (Display-free, prose at the binary
seam), member_metric over the 14 per-member scalars (third roster
site, refs #190 — drift fails safe as a preflight refusal), and
preflight: v1 pipeline shape std::sweep [std::gate]* [std::walk_forward],
rankable-metric and gate-metric rosters, plateau-in-wf and
deflate+plateau refusals, i64-fit guard on wf lengths — all before any
member runs.

Post-loop: the held quality finding (untested i64-fit arm) verified
real and closed by hand — preflight_refuses_wf_length_exceeding_i64.

Gates: aura-campaign 14/0, clippy -D warnings clean.

refs #198

Cargo.lock

@@ -105,6 +105,19 @@ dependencies = [
  "serde_json",
 ]
 
+[[package]]
+name = "aura-campaign"
+version = "0.1.0"
+dependencies = [
+ "aura-analysis",
+ "aura-core",
+ "aura-engine",
+ "aura-registry",
+ "aura-research",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "aura-cli"
 version = "0.1.0"