feat: 补全西班牙语i18n翻译

- 修正西班牙语代码为es

src/locale/es/units.json

@@ -0,0 +1,17 @@
+{
+  "mm": "mm",
+  "m": "m",
+  "g_per_cm3": "g/cm³",
+  "pcs": "uds.",
+  "kg": "kg",
+  "g_per_m2": "g/m²",
+  "hz": "Hz",
+  "hour": "h",
+  "percent": "%",
+  "m_per_min": "m/min",
+  "kg_per_hour": "kg/h",
+  "pcs_per_hour": "uds./h",
+  "kg_per_day": "kg/d",
+  "pcs_per_day": "uds./d",
+  "degree": "°"
+}