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/database/models.py

@@ -100,6 +100,10 @@ class Spool(Base):
     initial_weight: Mapped[Optional[float]] = mapped_column()
     spool_weight: Mapped[Optional[float]] = mapped_column()
     used_weight: Mapped[float] = mapped_column()
+    extra_weight: Mapped[Optional[float]] = mapped_column(
+        default=None,
+        comment="Extra weight to account for (DryPods, custom holders, etc.).",
+    )
     location: Mapped[Optional[str]] = mapped_column(String(64), comment="Legacy flat location string.")
     location_id: Mapped[Optional[int]] = mapped_column(
         ForeignKey("location.id", ondelete="SET NULL"),

spoolman/database/spool.py

@@ -41,6 +41,7 @@ async def create(
     remaining_weight: Optional[float] = None,
     initial_weight: Optional[float] = None,
     spool_weight: Optional[float] = None,
+    extra_weight: Optional[float] = None,
     used_weight: Optional[float] = None,
     first_used: Optional[datetime] = None,
     last_used: Optional[datetime] = None,
@@ -84,6 +85,7 @@ async def create(
         registered=datetime.utcnow().replace(microsecond=0),
         initial_weight=initial_weight,
         spool_weight=spool_weight,
+        extra_weight=extra_weight,
         used_weight=used_weight,
         price=price,
         first_used=first_used,
@@ -440,7 +442,12 @@ async def measure(
 
     """
     spool_result = await db.execute(
-        sqlalchemy.select(models.Spool.initial_weight, models.Spool.used_weight, models.Spool.spool_weight).where(
+        sqlalchemy.select(
+            models.Spool.initial_weight,
+            models.Spool.used_weight,
+            models.Spool.spool_weight,
+            models.Spool.extra_weight,
+        ).where(
             models.Spool.id == spool_id,
         ),
     )
@@ -452,6 +459,7 @@ async def measure(
 
     initial_weight = spool_info[0]
     spool_weight = spool_info[2]
+    extra_weight = spool_info[3] or 0  # Default to 0 if not set
     if initial_weight is None or initial_weight == 0 or spool_weight is None or spool_weight == 0:
         # Get filament weight and spool_weight
         result = await db.execute(
@@ -473,7 +481,7 @@ async def measure(
     if initial_weight is None or initial_weight == 0:
         raise SpoolMeasureError("Initial weight is not set.")
 
-    initial_gross_weight = initial_weight + spool_weight
+    initial_gross_weight = initial_weight + spool_weight + extra_weight
 
     # if the measurement is greater than the initial weight, set the initial weight to the measurement
     if weight > initial_gross_weight:
@@ -485,9 +493,10 @@ async def measure(
     # Calculate the weight used since last measure
     weight_to_use = current_use - weight
 
-    # If the measured weight is less than the empty weight, use the rest of the spool
-    if (initial_gross_weight - weight_to_use) < spool_weight:
-        weight_to_use = current_use - spool_weight
+    # If the measured weight is less than the empty weight (+ extra), use the rest of the spool
+    empty_gross_weight = spool_weight + extra_weight
+    if (initial_gross_weight - weight_to_use) < empty_gross_weight:
+        weight_to_use = current_use - empty_gross_weight
 
     return await use_weight(db, spool_id, weight_to_use, comment=comment)