feat(filament): add spool count and total remaining weight columns

Adds computed spool statistics to filament list:
- spool_count: Number of non-archived spools of this filament
- total_remaining_weight: Sum of remaining weight across all spools

Backend changes:
- Modified database/filament.py find() to compute stats via subquery
- Added fields to Filament pydantic model in api/v1/models.py
- Updated filament API endpoint to include stats in response

Frontend changes:
- Added fields to IFilament interface
- Added columns to filament list table
- Added translation keys

Closes #15

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

client/src/pages/filaments/list.tsx

@@ -65,6 +65,8 @@ const allColumns: (keyof IFilamentCollapsed & string)[] = [
   "article_number",
   "settings_extruder_temp",
   "settings_bed_temp",
+  "spool_count",
+  "total_remaining_weight",
   "registered",
   "comment",
 ];
@@ -324,6 +326,22 @@ export const FilamentList: React.FC<IResourceComponentsProps> = () => {
             maxDecimals: 0,
             width: 100,
           }),
+          NumberColumn({
+            ...commonProps,
+            id: "spool_count",
+            i18ncat: "filament",
+            unit: "",
+            maxDecimals: 0,
+            width: 80,
+          }),
+          NumberColumn({
+            ...commonProps,
+            id: "total_remaining_weight",
+            i18ncat: "filament",
+            unit: "g",
+            maxDecimals: 0,
+            width: 120,
+          }),
           DateColumn({
             ...commonProps,
             id: "registered",

client/src/pages/filaments/model.tsx

@@ -24,6 +24,8 @@ export interface IFilament {
   multi_color_direction?: string;
   external_id?: string;
   extra: { [key: string]: string };
+  spool_count?: number;
+  total_remaining_weight?: number;
 }
 
 // IFilamentParsedExtras is the same as IFilament, but with the extra field parsed into its real types