M1: notes model + migration 0002 + notes API (CRUD, trash/restore)

- Note model (owner_id, title, body, color-key, pinned, archived, deleted_at
  soft-delete, timestamps) + board index; NOTE_COLORS palette keys.
- Migration 0002 (notes table + ix_notes_owner_board).
- /api/notes blueprint (login_required): list (?filter=active|archived|trash,
  pinned-then-updated, read via visible_to_user ACL), create, get, patch
  (title/body/color/pinned/archived), trash, restore, permanent delete
  (trash-only). Mutations owner-scoped; empty note rejected (400).
- DB-free unit tests: is_empty_note, normalize_color, palette, serialize,
  auth-guard on list/create.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

src/thoughtsync/models/all.py

@@ -3,4 +3,4 @@
 Imported for side effects only (model registration on Base.metadata).
 """
 
-from . import group, share, user  # noqa: F401
+from . import group, note, share, user  # noqa: F401

src/thoughtsync/models/note.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Text, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from . import Base
+
+# The Keep-style palette. Stored as a key string, so the actual tints live in the
+# frontend and can change without a schema migration.
+NOTE_COLORS = {
+    "default",
+    "red",
+    "orange",
+    "yellow",
+    "green",
+    "teal",
+    "blue",
+    "purple",
+    "pink",
+    "gray",
+}
+
+
+class Note(Base):
+    __tablename__ = "notes"
+    __table_args__ = (
+        # Covers the board queries: a user's notes filtered by trash/archive state,
+        # pinned first.
+        Index("ix_notes_owner_board", "owner_id", "deleted_at", "archived", "pinned"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    owner_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+    )
+    title: Mapped[str | None] = mapped_column(Text(), nullable=True)
+    body: Mapped[str] = mapped_column(Text(), nullable=False, server_default="")
+    color: Mapped[str] = mapped_column(Text(), nullable=False, server_default="default")
+    pinned: Mapped[bool] = mapped_column(Boolean(), nullable=False, server_default=func.false())
+    archived: Mapped[bool] = mapped_column(Boolean(), nullable=False, server_default=func.false())
+    # Soft delete: non-null => in Trash. Restore sets it back to null.
+    deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    def serialize(self) -> dict:
+        return {
+            "id": str(self.id),
+            "title": self.title,
+            "body": self.body,
+            "color": self.color,
+            "pinned": self.pinned,
+            "archived": self.archived,
+            "trashed": self.deleted_at is not None,
+            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+        }