Phase 2/4 done, working on phase 3/5

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all frontend backend test clean
+.PHONY: all frontend backend backend-epics test test-epics clean
 
 all: frontend backend
 
@@ -8,6 +8,14 @@ frontend:
 backend:
 	go build -ldflags="-s -w" -o dist/uopi ./cmd/uopi
 
+# Build backend with EPICS Channel Access support.
+# Requires EPICS Base to be installed and the following environment variables:
+#   EPICS_BASE=/path/to/epics/base
+#   CGO_CFLAGS="-I${EPICS_BASE}/include -I${EPICS_BASE}/include/os/Linux"
+#   CGO_LDFLAGS="-L${EPICS_BASE}/lib/linux-x86_64 -lca -lCom"
+backend-epics:
+	CGO_ENABLED=1 go build -tags epics -ldflags="-s -w" -o dist/uopi ./cmd/uopi
+
 # Build backend without -s -w for debugging
 backend-debug:
 	go build -o dist/uopi ./cmd/uopi
@@ -16,6 +24,10 @@ test:
 	go test ./...
 	cd web && npm run check
 
+# Run EPICS integration tests (requires EPICS Base; see backend-epics target).
+test-epics:
+	go test -tags epics ./internal/datasource/epics/...
+
 lint:
 	go vet ./...
 	cd web && npm run lint