feat: Add color column with filter to spool list

Add optional color column to spool list showing filament color swatches
with multi-select filtering capability.

Backend:
- GET /api/v1/color endpoint to list distinct filament colors
- filament.color_hex query param on spool list for filtering

Frontend:
- ColorFilterColumn component renders color swatches
- useSpoolmanColors() hook fetches available colors
- Filter dropdown shows swatches with hex codes
- Column hidden by default (enable via column selector)

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

spoolman/database/filament.py

@@ -241,6 +241,16 @@ async def find_materials(
     return [row[0] for row in rows.all() if row[0] is not None]
 
 
+async def find_colors(
+    *,
+    db: AsyncSession,
+) -> list[str]:
+    """Find a list of unique filament colors (hex codes) from the filament table."""
+    stmt = select(models.Filament.color_hex).distinct()
+    rows = await db.execute(stmt)
+    return sorted([row[0] for row in rows.all() if row[0] is not None])
+
+
 async def find_article_numbers(
     *,
     db: AsyncSession,

spoolman/database/spool.py

@@ -118,6 +118,7 @@ async def find(  # noqa: C901, PLR0912
     filament_name: Optional[str] = None,
     filament_id: Optional[Union[int, Sequence[int]]] = None,
     filament_material: Optional[str] = None,
+    filament_color_hex: Optional[Union[str, Sequence[str]]] = None,
     vendor_name: Optional[str] = None,
     vendor_id: Optional[Union[int, Sequence[int]]] = None,
     location: Optional[str] = None,
@@ -152,6 +153,15 @@ async def find(  # noqa: C901, PLR0912
     stmt = add_where_clause_str_opt(stmt, models.Spool.location, location)
     stmt = add_where_clause_str_opt(stmt, models.Spool.lot_nr, lot_nr)
 
+    # Filter by color_hex (exact match, supports multiple comma-separated values)
+    if filament_color_hex is not None:
+        if isinstance(filament_color_hex, str):
+            colors = [c.strip() for c in filament_color_hex.split(",") if c.strip()]
+        else:
+            colors = list(filament_color_hex)
+        if colors:
+            stmt = stmt.where(models.Filament.color_hex.in_(colors))
+
     if not allow_archived:
         # Since the archived field is nullable, and default is false, we need to check for both false or null
         stmt = stmt.where(