Fix jumping field order, tidy labels/units on Dashboard field list

The unordered plant_asset_latest query could return rows in a different
order after every MQTT upsert, making the field list under each asset card
appear to shuffle. Added ORDER BY, plus a curated label/unit/order table
for the known water-softener fields (Salt Level 42%, Tank A Capacity
1850 L, Regeneration Active Yes/No, ...) with a title-case + alphabetical
fallback for anything not yet mapped.

backend/src/routes/status.js

@@ -14,9 +14,13 @@ export async function statusRoutes(app) {
       SELECT * FROM plant_assets WHERE active = TRUE ORDER BY asset_type, name
     `)
 
+    // ORDER BY matters here — without it, Postgres can return this heavily-
+    // upserted table's rows in a different order after every MQTT message,
+    // which made the Dashboard's field list appear to shuffle on refresh.
     const { rows: latest } = await pool.query(`
       SELECT asset_id, field_key, value_numeric, value_text, updated_at
       FROM plant_asset_latest
+      ORDER BY asset_id, field_key
     `)
     const latestByAsset = new Map()
     for (const l of latest) {