create channel<->note join table

lib/chiya/channels/channel_note.ex

@@ -0,0 +1,19 @@
+defmodule Chiya.Channels.ChannelNote do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "channels_notes" do
+
+    field :channel, :id
+    field :note, :id
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(channel_note, attrs) do
+    channel_note
+    |> cast(attrs, [])
+    |> validate_required([])
+  end
+end

priv/repo/migrations/20230305171255_create_channels_notes.exs

@@ -0,0 +1,15 @@
+defmodule Chiya.Repo.Migrations.CreateChannelsNotes do
+  use Ecto.Migration
+
+  def change do
+    create table(:channels_notes) do
+      add :channel, references(:channels, on_delete: :nothing)
+      add :note, references(:notes, on_delete: :nothing)
+
+      timestamps()
+    end
+
+    create index(:channels_notes, [:channel])
+    create index(:channels_notes, [:note])
+  end
+end