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>

migrations/versions/2025_01_21_0200-f6g7h8i9j0k1_add_spool_extra_weight.py

@@ -0,0 +1,31 @@
+"""Add extra_weight field to spool for DryPods, custom holders, etc.
+
+Revision ID: f6g7h8i9j0k1
+Revises: e5f6g7h8i9j0
+Create Date: 2025-01-21 22:00:00.000000
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "f6g7h8i9j0k1"
+down_revision = "e5f6g7h8i9j0"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "spool",
+        sa.Column(
+            "extra_weight",
+            sa.Float(),
+            nullable=True,
+            comment="Extra weight to account for (DryPods, custom holders, etc.).",
+        ),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("spool", "extra_weight")