Add state-hub v0.1 — local-first state service for the Custodian

Implements the first live layer of the Custodian cognitive infrastructure:
PostgreSQL schema, FastAPI REST API, FastMCP stdio server, and Observable
Framework telemetry dashboard.

- state-hub/: full stack (docker-compose, FastAPI, Alembic, MCP server, dashboard)
- 5 DB tables: topics, workstreams, tasks, decisions, progress_events
- 11 MCP tools + 5 resources registered in .mcp.json
- Observable dashboard: Overview, Workstreams, Decisions, Progress pages
- CLAUDE.md: session protocol (get_state_summary / add_progress_event ritual)
- ~/.claude/CLAUDE.md: global cross-project reference to the hub
- scripts/pull_image.py: WSL2 TLS-resilient Docker image downloader

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/models/workstream.py

@@ -0,0 +1,46 @@
+import enum
+import uuid
+from datetime import date
+
+from sqlalchemy import Date, Enum, ForeignKey, String, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from api.models.base import Base, TimestampMixin, new_uuid
+
+
+class WorkstreamStatus(str, enum.Enum):
+    active = "active"
+    blocked = "blocked"
+    completed = "completed"
+    archived = "archived"
+
+
+class Workstream(Base, TimestampMixin):
+    __tablename__ = "workstreams"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=new_uuid
+    )
+    topic_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("topics.id", ondelete="RESTRICT"), nullable=False, index=True
+    )
+    slug: Mapped[str] = mapped_column(String(100), unique=True, nullable=False, index=True)
+    title: Mapped[str] = mapped_column(String(255), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    status: Mapped[WorkstreamStatus] = mapped_column(
+        Enum(WorkstreamStatus), nullable=False, default=WorkstreamStatus.active
+    )
+    owner: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    due_date: Mapped[date | None] = mapped_column(Date, nullable=True)
+
+    topic: Mapped["Topic"] = relationship("Topic", back_populates="workstreams")  # noqa: F821
+    tasks: Mapped[list["Task"]] = relationship(  # noqa: F821
+        "Task", back_populates="workstream", lazy="selectin"
+    )
+    decisions: Mapped[list["Decision"]] = relationship(  # noqa: F821
+        "Decision", back_populates="workstream", lazy="selectin"
+    )
+    progress_events: Mapped[list["ProgressEvent"]] = relationship(  # noqa: F821
+        "ProgressEvent", back_populates="workstream", lazy="selectin"
+    )