Add tests

Makefile

@@ -11,7 +11,7 @@ RELEASE_FLAGS := -trimpath -ldflags="-s -w"
 EDITOR_BUNDLE := assets/editor/vendor/codemirror.bundle.js
 EDITOR_SRCS := $(wildcard editor-build/*.js) editor-build/package.json editor-build/package-lock.json
 
-.PHONY: deploy companion companion-windows companion-linux companion-release editor
+.PHONY: deploy companion companion-windows companion-linux companion-release editor e2e
 
 # Cross-compiled companion artifacts the wiki binary embeds. Both must exist
 # before `go build .` so embed.FS picks them up.
@@ -46,3 +46,8 @@ deploy: companion-release
 	scp datascape-arm $(NAS):/share/homes/luxick/.local/bin/datascape
 	ssh $(NAS) /share/homes/luxick/.local/bin/datascape-start.sh
 	rm datascape-arm
+
+# Browser end-to-end tests (Playwright driving the system Chrome). Builds the
+# wiki binary and runs it against a throwaway wiki in e2e/.tmp.
+e2e:
+	cd e2e && npm install --no-audit --no-fund && npx playwright test