Phase 8: add the Reference App wiki walkthrough (06_reference_app)

- four pages walking the vet sample: overview, domain & API, pipelines &
  worker, spec-driven client admin
- mkdocs nav section, index + start-an-app cross links
- bundle now exposes the walkthrough as wiki_reference_app_* modules

standards/src/wiki/index.md

@@ -38,6 +38,7 @@ the same shape underneath.
 | [Overview](01_overview.md)                          | Philosophy, the one-way dependency rule, architecture  |
 | [App Components](02_components.md)                  | The component model and how the pieces wire together   |
 | [Start an App](03_start_an_app.md)                  | The entry point: gather the two axes, then build       |
+| [Reference App](06_reference_app/01_overview.md)    | The runnable vet sample — server, pipelines, client    |
 | [Testing & Quality](04_development/01_testing.md)   | Test layout and acceptance gates                       |
 
 **Reference** (separate site, mirrors the MCP bundle): the enforceable
@@ -63,7 +64,9 @@ Registry](../lib/93_library_registry/)).
   `docs://nav`, `docs://modules/{module}`; call `find_library(capability)`
 - **Library registry** — the catalog of internal libraries behind every app
   (`libraries.json`, served as `registry://libraries`)
-- **Template** — the runnable skeleton at `standards/src/templates/app/`
+- **Template** — the runnable sample at `standards/src/templates/app/`
+  (server) and `standards/src/templates/client/` (React admin); walkthrough in
+  the [Reference App](06_reference_app/01_overview.md)
 - **Start a build** — invoke the `start_app` prompt on the `standards` server,
   or read the [Start an App](03_start_an_app.md) guide