feat(scenarios,environments): add markdown description field

- add optional description to scenario and environment entities
- expose description in create/update DTOs, MCP tools, and export DTOs
- render description as markdown on detail pages
- add description editor (CodeEditor) to create/edit forms for both resources

server/Dockerfile

@@ -35,7 +35,7 @@ RUN npm ci --omit=dev -w server
 COPY --from=builder /app/server/dist ./dist
 
 # Runtime directories (keys and SQLite DB mounted via volumes)
-RUN mkdir -p data keys
+RUN mkdir -p data
 
 EXPOSE 3000