feat: modernize application — source, platform artifacts, CI/CD

- chore: ingest source code

112 files from https://github.com/spring-projects/spring-petclinic
- feat: add platform deployment artifacts
- feat: add CI/CD workflow automation

mkdocs.yml

@@ -0,0 +1,13 @@
+site_name: demo-sergio
+site_description: Modernized demo-sergio service
+
+nav:
+  - Home: index.md
+  - Architecture: architecture.md
+  - API Reference: api.md
+
+plugins:
+  - techdocs-core
+
+theme:
+  name: material