feat(ops): add k3s + ArgoCD GitOps pipeline

- Dockerfile: copy web/ and assets/ to runtime stage so ServeDir routes work
- .gitea/workflows/docker-build.yml: build/push image on master push, pin SHA
  tag back into deploy/kustomization.yaml so ArgoCD sees a real manifest change
- deploy/: Kustomize manifests — Namespace, PVC, Deployment (Recreate for
  SQLite), Service, Traefik Ingress at klondike.aleshym.co
- argocd/application.yaml: auto-sync Application watching deploy/ on Gitea

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_server/Dockerfile

@@ -48,8 +48,12 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 WORKDIR /app
 
 COPY --from=builder /build/target/release/solitaire_server ./solitaire_server
-# Migrations are embedded via sqlx::migrate!("./migrations") relative to the
-# crate root at compile time — they do not need to be copied here.
+# Migrations are embedded via sqlx::migrate!("./migrations") at compile time.
+# Static web assets are served via ServeDir at runtime from these paths:
+#   /app/solitaire_server/web  →  /web route
+#   /app/assets                →  /assets route
+COPY solitaire_server/web ./solitaire_server/web
+COPY assets ./assets
 
 ENV SERVER_PORT=8080
 EXPOSE 8080