feat: Add extra weight, price tracking, print history, usage analytics

- Extra Weight Field (#14): Track DryPods, custom holders in spool weight
  calculations. New extra_weight field on spool with DB migration.

- Price/Cost Tracking: Compute remaining_value based on remaining weight
  and price. Added column to spool list, inventory value on dashboard.

- Print History: Show print job history on spool detail page with
  collapsible table showing filename, filament used, status, dates.

- Usage Analytics: New dashboard component with time-series chart
  showing daily consumption, period selector (7/30/90 days), and
  material breakdown. New API endpoints for analytics data.

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

spoolman/api/v1/spool.py

@@ -51,6 +51,12 @@ class SpoolParameters(BaseModel):
         description="The weight of an empty spool, in grams. (tare weight)",
         examples=[200],
     )
+    extra_weight: Optional[float] = Field(
+        None,
+        ge=0,
+        description="Extra weight to account for, such as DryPods, custom spool holders, etc., in grams.",
+        examples=[50],
+    )
     remaining_weight: Optional[float] = Field(
         None,
         ge=0,
@@ -449,6 +455,7 @@ async def create(  # noqa: ANN201
             price=body.price,
             initial_weight=body.initial_weight,
             spool_weight=body.spool_weight,
+            extra_weight=body.extra_weight,
             remaining_weight=body.remaining_weight,
             used_weight=body.used_weight,
             first_used=body.first_used,