chore: install opencode in ddev container for security reasons

.ddev/addon-metadata/opencode/manifest.yaml

@@ -0,0 +1,11 @@
+name: opencode
+repository: /Users/fromme/Development/Misc/ddev-opencode
+version: ""
+install_date: "2026-01-05T16:57:43+01:00"
+project_files:
+    - web-build/Dockerfile.opencode
+    - commands/web/opencode
+    - config.opencode.yaml
+    - opencode/.gitignore
+global_files: []
+removal_actions: []