fieldtest: cycle-241 wiring-only tier — 4 axes, 1 bug + 4 friction + 1 spec_gap + 5 working

Consumer-POV fieldtest evidence for the two-tier project model: the
data-only quickstart, the role-2 attach loop, real-data usage inside a
data-only project, and the refusal surfaces all match the docs.

Inline fixes for two of the friction findings:
- docs/project-layout.md: the day-in-the-life run example now shows real
  Unix-ms window bounds instead of bare years (--from/--to take ms).
- `aura new` --help one-liner no longer calls the project a crate.

Remaining findings tracked on the Gitea queue (empty first-manifest
provenance on a fresh scaffold; misleading no-data message for an
uncovered --real window; the tier hint missing on the graph-build path;
the raw cargo-metadata leak for a missing [nodes] dir).

refs #241

crates/aura-cli/src/main.rs

@@ -2453,7 +2453,7 @@ enum Command {
     Runs(RunsCmd),
     /// Reproduce a recorded family by content id.
     Reproduce(ReproduceCmd),
-    /// Scaffold a new research project crate.
+    /// Scaffold a new data-only research project.
     New(NewCmd),
     /// Scaffold and attach node crates (native-node development).
     Nodes(NodesCmd),