printedparts stage 1: scaffold, no AssetType, manifest per spec

flask plugin new output, minus the scaffold's AssetType seeding:
printed parts are quantity-based consumables, not ADR-001 assets.
on_install seeds the three plugin settings instead. Manifest pins
core >=0.11.0, depends on employees (badge name resolution), ships
disabled until a site opts in.

plugins/printedparts/models/__init__.py

@@ -0,0 +1,5 @@
+"""Printedparts plugin models."""
+
+from .printedparts import Printedparts
+
+__all__ = ['Printedparts']

plugins/printedparts/models/printedparts.py

@@ -0,0 +1,32 @@
+"""Printedparts model.
+
+This is an Asset extension table keyed by assetid. The Asset row holds
+the platform fields (assetnumber, name, vendorid, locationid, etc.);
+this table holds the printedparts-specific fields. Replace the example fields
+below with your domain model.
+"""
+
+from shopdb.api import db, BaseModel
+
+
+class Printedparts(BaseModel):
+    """Printedparts domain entity, extending Asset by assetid."""
+
+    __tablename__ = 'printedparts'
+
+    assetid = db.Column(
+        db.Integer,
+        db.ForeignKey('assets.assetid', ondelete='CASCADE'),
+        primary_key=True,
+    )
+
+    # TODO: replace these example fields with your domain fields.
+    examplefield = db.Column(db.String(255), nullable=True)
+
+    asset = db.relationship('Asset', backref=db.backref('printedparts', uselist=False))
+
+    def to_dict(self):
+        return {
+            'assetid': self.assetid,
+            'examplefield': self.examplefield,
+        }