Complete flex-auth PEP and document railiance packaging path

Local + HTTP POST /v1/check PEP with fail-closed transport errors;
shell:view enforced on /app/. Vocabulary docs for T07. Helm chart lives
in railiance-apps; Dockerfile already present for T08.

coulomb_social/templates/core/app_home.html

@@ -13,6 +13,7 @@
       <dt>Subject</dt><dd>{{ principal.subject }}</dd>
       <dt>user-engine id</dt><dd>{{ principal.user_engine_user_id }}</dd>
       <dt>user-engine source</dt><dd>{{ principal.user_engine_source|default:"—" }}</dd>
+      <dt>authz</dt><dd>{{ principal.authz_reason }} <span class="muted">({{ principal.authz_decision_id }})</span></dd>
     </dl>
   </div>
 {% endblock %}