Fix temp range display in show page and label templates

- Show page now displays temp ranges (min-max) instead of single values
- Fixed label template rendering to handle multiple tags in conditional blocks
- Added "not_set" translation key

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

client/public/locales/en/common.json

@@ -254,7 +254,8 @@
             "coaxial": "Coextruded",
             "longitudinal": "Longitudinal",
             "external_id": "External ID",
-            "spools": "Show Spools"
+            "spools": "Show Spools",
+            "not_set": "Not Set"
         },
         "fields_help": {
             "name": "Filament name, to distinguish this filament type among others from the same manufacturer. Should contain the color for example.",