add fixture-invoicing example, sample-room wrap, kind cluster support

- examples/fixture-invoicing/: FastAPI + Vue + Postgres demo (4-entity invoice fixture)
- cfg/sample/: wraps the fixture (managed.repos points at examples/)
- ctrl/kind-{up,down,status}.sh + per-room k8s render in soleprint/ctrl/k8s/
- build.py: relative repo paths, resilient rmtree, optional k8s render hook
- cfg/.gitignore: stop ignoring sample/ and standalone/ template rooms

Manifests render cleanly but kind cluster has not been run end-to-end yet.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/fixture-invoicing/backend/models.py

@@ -0,0 +1,63 @@
+from datetime import datetime
+from decimal import Decimal
+
+from sqlalchemy import DateTime, ForeignKey, Integer, Numeric, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from db import Base
+
+
+class Customer(Base):
+    __tablename__ = "customer"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    name: Mapped[str] = mapped_column(String(120), nullable=False)
+    email: Mapped[str] = mapped_column(String(200), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+
+    invoices: Mapped[list["Invoice"]] = relationship(
+        back_populates="customer", cascade="all, delete-orphan"
+    )
+
+
+class Invoice(Base):
+    __tablename__ = "invoice"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    number: Mapped[str] = mapped_column(String(40), nullable=False, unique=True)
+    customer_id: Mapped[int] = mapped_column(ForeignKey("customer.id"), nullable=False)
+    issued_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+    due_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    status: Mapped[str] = mapped_column(String(20), default="draft")
+
+    customer: Mapped[Customer] = relationship(back_populates="invoices")
+    line_items: Mapped[list["LineItem"]] = relationship(
+        back_populates="invoice", cascade="all, delete-orphan"
+    )
+    payments: Mapped[list["Payment"]] = relationship(
+        back_populates="invoice", cascade="all, delete-orphan"
+    )
+
+
+class LineItem(Base):
+    __tablename__ = "line_item"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    invoice_id: Mapped[int] = mapped_column(ForeignKey("invoice.id"), nullable=False)
+    description: Mapped[str] = mapped_column(String(200), nullable=False)
+    quantity: Mapped[int] = mapped_column(Integer, default=1)
+    unit_price: Mapped[Decimal] = mapped_column(Numeric(10, 2), default=0)
+
+    invoice: Mapped[Invoice] = relationship(back_populates="line_items")
+
+
+class Payment(Base):
+    __tablename__ = "payment"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    invoice_id: Mapped[int] = mapped_column(ForeignKey("invoice.id"), nullable=False)
+    amount: Mapped[Decimal] = mapped_column(Numeric(10, 2), nullable=False)
+    method: Mapped[str] = mapped_column(String(20), default="cash")
+    paid_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+
+    invoice: Mapped[Invoice] = relationship(back_populates="payments")