refactor: user specific canvas state (#1936)

* feat: add user_canvases table and related functionality

- Created a new table "user_canvases" to store user-specific canvas data including scale, x, and y coordinates.
- Implemented row-level security and foreign key constraints for user and canvas references.
- Added migration to copy existing canvas data to the new user_canvases table.
- Updated project and canvas routers to handle user canvas retrieval and updates.
- Introduced utility functions for creating default user canvas entries.
- Adjusted relevant components to utilize user canvas data instead of general canvas data.

* feat: enhance user canvas retrieval in project router

- Added userCanvases filter in project router to restrict canvas access based on user ID.
- Refactored user canvas query in user-canvas router for improved readability and efficiency.
- Updated logic to return null if no user canvas is found, ensuring better error handling.

Author: satya-nutella

apps/backend/supabase/migrations/0003_loud_ozymandias.sql

@@ -0,0 +1,28 @@
+CREATE TABLE "user_canvases" (
+	"user_id" uuid NOT NULL,
+	"canvas_id" uuid NOT NULL,
+	"scale" numeric NOT NULL,
+	"x" numeric NOT NULL,
+	"y" numeric NOT NULL,
+	CONSTRAINT "user_canvases_user_id_canvas_id_pk" PRIMARY KEY("user_id","canvas_id")
+);
+--> statement-breakpoint
+ALTER TABLE "user_canvases" ENABLE ROW LEVEL SECURITY;--> statement-breakpoint
+ALTER TABLE "user_canvases" ADD CONSTRAINT "user_canvases_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE cascade;--> statement-breakpoint
+ALTER TABLE "user_canvases" ADD CONSTRAINT "user_canvases_canvas_id_canvas_id_fk" FOREIGN KEY ("canvas_id") REFERENCES "public"."canvas"("id") ON DELETE cascade ON UPDATE cascade;--> statement-breakpoint
+
+-- Copy over the scale, x, and y values from the canvas table to the user_canvases table
+INSERT INTO "user_canvases" ("user_id", "canvas_id", "scale", "x", "y")
+SELECT 
+    up.user_id,
+    c.id as canvas_id,
+    c.scale,
+    c.x,
+    c.y
+FROM "canvas" c
+INNER JOIN "user_projects" up ON c.project_id = up.project_id
+ON CONFLICT (user_id, canvas_id) DO NOTHING;
+
+ALTER TABLE "canvas" DROP COLUMN "scale";--> statement-breakpoint
+ALTER TABLE "canvas" DROP COLUMN "x";--> statement-breakpoint
+ALTER TABLE "canvas" DROP COLUMN "y";