feat(backend): init aris-backend with Hono

- Add apps/aris-backend package with Hono server
- Add /health endpoint
- Add backend-spec.md with design decisions

Co-authored-by: Ona <no-reply@ona.com>

apps/aris-backend/tsconfig.json

@@ -0,0 +1,7 @@
+{
+	"extends": "../../tsconfig.json",
+	"compilerOptions": {
+		"types": ["bun-types"]
+	},
+	"include": ["src"]
+}