fix(spool): Add remaining_weight filter for low stock detection

- Add remaining_weight_lt and remaining_weight_gt filter params to spool API
- Filter uses computed formula: initial_weight - used_weight (falls back to filament.weight)
- Update home page to use queryParams instead of Refine filters
- Fixes low stock badge count on dashboard

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

spoolman/api/v1/spool.py

@@ -268,6 +268,20 @@ async def find(
         Optional[bool],
         Query(title="Needs Weighing", description="Filter by spools that need manual weigh-in."),
     ] = None,
+    remaining_weight_lt: Annotated[
+        Optional[float],
+        Query(
+            title="Remaining Weight Less Than",
+            description="Filter by spools with remaining weight (in grams) less than this value.",
+        ),
+    ] = None,
+    remaining_weight_gt: Annotated[
+        Optional[float],
+        Query(
+            title="Remaining Weight Greater Than",
+            description="Filter by spools with remaining weight (in grams) greater than this value.",
+        ),
+    ] = None,
     sort: Annotated[
         Optional[str],
         Query(
@@ -313,6 +327,8 @@ async def find(
         lot_nr=lot_nr,
         allow_archived=allow_archived,
         needs_weighing=needs_weighing,
+        remaining_weight_lt=remaining_weight_lt,
+        remaining_weight_gt=remaining_weight_gt,
         sort_by=sort_by,
         limit=limit,
         offset=offset,

spoolman/database/spool.py

@@ -124,6 +124,8 @@ async def find(  # noqa: C901, PLR0912
     lot_nr: Optional[str] = None,
     allow_archived: bool = False,
     needs_weighing: Optional[bool] = None,
+    remaining_weight_lt: Optional[float] = None,
+    remaining_weight_gt: Optional[float] = None,
     sort_by: Optional[dict[str, SortOrder]] = None,
     limit: Optional[int] = None,
     offset: int = 0,
@@ -170,6 +172,13 @@ async def find(  # noqa: C901, PLR0912
                 ),
             )
 
+    # Filter by remaining_weight (computed as initial_weight - used_weight, falling back to filament.weight)
+    remaining_weight_expr = coalesce(models.Spool.initial_weight, models.Filament.weight) - models.Spool.used_weight
+    if remaining_weight_lt is not None:
+        stmt = stmt.where(remaining_weight_expr < remaining_weight_lt)
+    if remaining_weight_gt is not None:
+        stmt = stmt.where(remaining_weight_expr > remaining_weight_gt)
+
     total_count = None
 
     if limit is not None: