feat(image): add scratch container image

Two-stage build producing a static /app on scratch; e2e tests for image contents, server and CLI through docker exec, socket handling, lifecycle and host/image parity.

.dockerignore

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+.git
+.gitignore
+.dockerignore
+LICENSE
+dockerfile
+makefile
+.vars
+vars.example
+.cursor
+*.md
+*.sh
+dpsapi
+data
+**/*.db
+**/*.db-*
+coverage.out
+*.cov
+e2e
+**/node_modules
+test-results
+playwright-report