feat(FN-011): complete Step 4 — repository connection model and connection manager

Fusion-Task-Id: FN-011
Fusion-Task-Lineage: 4a9aca6f-9d91-43aa-8d2a-d59657c1541a

apps/api/app/models/repository_connection.py

@@ -0,0 +1,39 @@
+"""RepositoryConnection links a project to a Git repository via a provider."""
+
+import uuid
+from typing import TYPE_CHECKING
+
+from sqlalchemy import ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base, TimestampMixin, UUIDMixin
+
+if TYPE_CHECKING:
+    from app.models.repository import Repository
+
+
+class RepositoryConnection(Base, UUIDMixin, TimestampMixin):
+    __tablename__ = "repository_connection"
+
+    project_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("project.id"), index=True
+    )
+    repository_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("repository.id"), nullable=True, index=True
+    )
+    provider_kind: Mapped[str] = mapped_column(
+        String(50), default="generic"
+    )
+    credential_id: Mapped[uuid.UUID | None] = mapped_column(
+        index=True, nullable=True
+    )
+    connection_status: Mapped[str] = mapped_column(
+        String(50), default="pending"
+    )
+    default_branch: Mapped[str | None] = mapped_column(
+        String(100), nullable=True
+    )
+
+    repository: Mapped["Repository"] = relationship(
+        back_populates="connections"
+    )