fix(widget-secrets): add missing widget_secret migration and add error notifications

The widget_secret table was defined in all three Drizzle schema files but
no SQL migration was ever generated to create it, causing setSecret to
fail with 'no such table: widget_secret' in production (drizzle-kit push
in development hid the problem).

- Add migration SQL for sqlite (0040), mysql (0042), postgresql (0008)
- Update journal entries for all three dialects
- Add onError handlers to setSecret/deleteSecret mutations so errors
  are shown as red notifications instead of silently swallowed

Fixes #6186

packages/db/migrations/postgresql/0008_add_widget_secret.sql

@@ -0,0 +1,9 @@
+CREATE TABLE "widget_secret" (
+	"item_id" varchar(64) NOT NULL,
+	"kind" varchar(64) NOT NULL,
+	"value" text NOT NULL,
+	"updated_at" timestamp NOT NULL,
+	CONSTRAINT "widget_secret_item_id_kind_pk" PRIMARY KEY("item_id","kind")
+);
+--> statement-breakpoint
+ALTER TABLE "widget_secret" ADD CONSTRAINT "widget_secret_item_id_item_id_fk" FOREIGN KEY ("item_id") REFERENCES "public"."item"("id") ON DELETE cascade ON UPDATE no action;

packages/db/migrations/postgresql/meta/_journal.json

@@ -57,6 +57,13 @@
       "when": 1780764500000,
       "tag": "0007_merge_custom_widget_url",
       "breakpoints": true
+    },
+    {
+      "idx": 8,
+      "version": "7",
+      "when": 1783176100870,
+      "tag": "0008_add_widget_secret",
+      "breakpoints": true
     }
   ]
 }