Add core data model (12 tables) and initial Alembic migration

All core entities from ARCHITECTURE §5: tenancy (User, Tree, TreeMembership), people (Person, Name, Relationship), facts (Event, Place, PlaceName), provenance (Source, Citation), and the append-only AuditEntry. Cross-cutting mixins give every row a UUID key, timestamps, soft delete, and (where tree-owned) a tree_id for uniform tenant isolation.

Modeling choices: parentage as qualified edges (biological/adoptive/step/foster/donor/guardian) so non-traditional families are first-class; events keep both a verbatim date string and a normalized start/end range; closed sets are PG enums while GEDCOM-extensible vocabularies (event/name/source type) stay strings; CHECK constraints enforce single-subject events and single-target citations. Place is tree-scoped in Phase 0 (see ARCHITECTURE note). The migration is verified reversible (upgrade/downgrade drops tables and enum types) and matches the models (alembic check clean); applied on the deploy target. Dockerfile now ships migrations.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

backend/app/models/source.py

@@ -0,0 +1,66 @@
+"""Source and Citation — the first-class provenance spine.
+
+A Source is a reusable record of an origin; a Citation links one Source to one
+specific fact (a Person, Name, Event, or Relationship — and OwnershipEvent once
+property lands). A CHECK enforces exactly one target so a citation always points
+at a single fact.
+"""
+
+import uuid
+
+from sqlalchemy import CheckConstraint, ForeignKey, String, Text
+from sqlalchemy import Enum as SAEnum
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.models.base import Base
+from app.models.enums import CitationConfidence
+from app.models.mixins import SoftDelete, TenantScoped, Timestamps, UUIDPrimaryKey
+
+
+class Source(Base, UUIDPrimaryKey, TenantScoped, Timestamps, SoftDelete):
+    __tablename__ = "sources"
+
+    title: Mapped[str] = mapped_column(String(512))
+    author: Mapped[str | None] = mapped_column(String(255))
+    source_type: Mapped[str | None] = mapped_column(String(64))  # book, census, deed, ...
+    repository: Mapped[str | None] = mapped_column(String(255))
+    url: Mapped[str | None] = mapped_column(String(1024))
+    citation_text: Mapped[str | None] = mapped_column(Text)
+    publication_info: Mapped[str | None] = mapped_column(Text)
+    quality_note: Mapped[str | None] = mapped_column(String(255))
+
+
+class Citation(Base, UUIDPrimaryKey, TenantScoped, Timestamps, SoftDelete):
+    __tablename__ = "citations"
+    __table_args__ = (
+        CheckConstraint(
+            "(person_id IS NOT NULL)::int + (event_id IS NOT NULL)::int "
+            "+ (name_id IS NOT NULL)::int + (relationship_id IS NOT NULL)::int = 1",
+            name="exactly_one_target",
+        ),
+    )
+
+    source_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("sources.id", ondelete="CASCADE"), index=True
+    )
+
+    # Exactly one of these is set (see CHECK above).
+    person_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("persons.id", ondelete="CASCADE"), index=True
+    )
+    event_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("events.id", ondelete="CASCADE"), index=True
+    )
+    name_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("names.id", ondelete="CASCADE"), index=True
+    )
+    relationship_id: Mapped[uuid.UUID | None] = mapped_column(
+        ForeignKey("relationships.id", ondelete="CASCADE"), index=True
+    )
+
+    # Locality within the source.
+    page: Mapped[str | None] = mapped_column(String(255))
+    detail: Mapped[str | None] = mapped_column(Text)  # entry, line, free notes
+    confidence: Mapped[CitationConfidence | None] = mapped_column(
+        SAEnum(CitationConfidence, name="citation_confidence")
+    )