feat(issues): S1 schema — issue task_kind, System entity, associations

First slice of the Issues + Systems feature (spec #825, plan #819 T2).

Schema (migration 0065):
- task_kind CHECK expands work|plan -> work|plan|issue (same-change, rule 36)
- notes.arose_from_id: optional self-FK for issue->originating-task provenance
  (distinct from parent_id sub-task hierarchy)
- systems: per-project, self-describing (name + description) subsystem/area
- record_systems: M2M join linking any note/task/issue to systems (mutable)

Models: System + RecordSystem; note.py gains arose_from_id (+ index, to_dict).
Service services/systems.py: CRUD, archive, soft-delete, set/list associations,
records-for-system, open-issue count — all gated via services/access.py project
permissions (rule 78, no bare-owner filters). Unit tests lock the ACL gating;
the migration is exercised by CI's integration lane (alembic upgrade head).

is_task stays a derived property (status is not None) — unchanged. T1 (typing-
axis rationalization) intentionally NOT bundled; this only adds the enum value.

Refs plan 825 (S1).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/scribe/models/note.py

@@ -40,6 +40,12 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
     parent_id: Mapped[int | None] = mapped_column(
         Integer, ForeignKey("notes.id", ondelete="SET NULL"), nullable=True
     )
+    # Provenance: the task/feature an issue arose from. Distinct from parent_id
+    # (sub-task hierarchy) — this is "what spawned this". Only meaningful for
+    # issues; nullable for every record.
+    arose_from_id: Mapped[int | None] = mapped_column(
+        Integer, ForeignKey("notes.id", ondelete="SET NULL"), nullable=True
+    )
     project_id: Mapped[int | None] = mapped_column(
         Integer, ForeignKey("projects.id", ondelete="SET NULL"), nullable=True
     )
@@ -60,9 +66,10 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
     # Structured metadata for entity types (person/place/list)
     # Named 'entity_meta' to avoid collision with SQLAlchemy's reserved 'metadata' attribute
     entity_meta: Mapped[dict | None] = mapped_column("metadata", JSONB, nullable=True)
-    # Task sub-kind — 'work' (default) or 'plan'. Only meaningful when the note
-    # is a task (status is not None); ordinary notes keep the 'work' default and
-    # ignore it. Orthogonal to note_type (which is the note/entity axis).
+    # Task sub-kind — 'work' (default), 'plan', or 'issue' (corrective work).
+    # Only meaningful when the note is a task (status is not None); ordinary
+    # notes keep the 'work' default and ignore it. Orthogonal to note_type
+    # (which is the note/entity axis).
     task_kind: Mapped[str] = mapped_column(Text, default="work", server_default="work")
 
     __table_args__ = (
@@ -73,6 +80,7 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
         Index("ix_notes_project_id", "project_id"),
         Index("ix_notes_milestone_id", "milestone_id"),
         Index("ix_notes_note_type", "note_type"),
+        Index("ix_notes_arose_from_id", "arose_from_id"),
     )
 
     @property
@@ -95,6 +103,7 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
             ),
             "tags": self.tags or [],
             "parent_id": self.parent_id,
+            "arose_from_id": self.arose_from_id,
             "project_id": self.project_id,
             "milestone_id": self.milestone_id,
             "status": self.status,