squash a bunch of commits

Shogi.Database/Session/Tables/BoardState.sql

@@ -0,0 +1,10 @@
+CREATE TABLE [session].[BoardState]
+(
+	[Id] BIGINT NOT NULL PRIMARY KEY IDENTITY,
+	[Document] NVARCHAR(max) NOT NULL,
+	[SessionId] BIGINT NOT NULL,
+
+	CONSTRAINT [Document must be json] CHECK (isjson(Document)=1),
+	CONSTRAINT FK_BoardState_Session FOREIGN KEY (SessionId) 
+		REFERENCES [session].[Session] (Id) ON DELETE CASCADE ON UPDATE CASCADE
+)

Shogi.Database/Session/Tables/Session.sql

@@ -0,0 +1,16 @@
+CREATE TABLE [session].[Session]
+(
+	Id			BIGINT NOT NULL PRIMARY KEY IDENTITY,
+	[Name]		[session].[SessionName] NOT NULL UNIQUE,
+	Created		DATETIMEOFFSET NOT NULL DEFAULT SYSDATETIMEOFFSET(),
+	GameOver	BIT NOT NULL DEFAULT 0,
+	Player1Id	BIGINT NOT NULL,
+	Player2Id	BIGINT NULL,
+
+	CONSTRAINT FK_Player1_User FOREIGN KEY (Player1Id) REFERENCES [user].[User] (Id) 
+		ON DELETE CASCADE 
+		ON UPDATE CASCADE,
+	CONSTRAINT FK_Player2_User FOREIGN KEY (Player2Id) REFERENCES [user].[User] (Id) 
+		ON DELETE NO ACTION
+		ON UPDATE NO ACTION
+)