Update project to use zod v4 (#18)

* Initial plan

* Complete zod v4 migration with updated import syntax and documentation

Co-authored-by: ondrejsevcik <[email protected]>

* Delete MIGRATION-ZOD-V4.md

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: ondrejsevcik <[email protected]>

Author: Copilot

package-lock.json

@@ -14,7 +14,7 @@
 		"@mozilla/readability": "^0.6.0",
 		"vite": "^6.3.5",
 		"vite-plugin-web-extension": "^4.4.3",
-		"zod": "^3.25.55"
+		"zod": "^4.1.5"
 	},
 	"engines": {
 		"node": ">=22.14.0"

package.json

@@ -1,22 +1,20 @@
-import zod from "zod";
+import { z } from "zod";
 
-export const MessageSchema = zod.object({
-	action: zod.string(),
-	payload: zod.unknown(),
+export const MessageSchema = z.object({
+	action: z.string(),
+	payload: z.unknown(),
 });
 
-export type Message = zod.infer<typeof MessageSchema>;
+export type Message = z.infer<typeof MessageSchema>;
 
-export const PromptSchema = zod.object({
-	promptText: zod
+export const PromptSchema = z.object({
+	promptText: z
 		.string()
 		.min(1, "Prompt text must be at least 1 character long"),
-	attachment: zod
-		.string()
-		.min(1, "Attachment must be at least 1 character long"),
+	attachment: z.string().min(1, "Attachment must be at least 1 character long"),
 });
 
-export type Prompt = zod.infer<typeof PromptSchema>;
+export type Prompt = z.infer<typeof PromptSchema>;
 
 export const GET_CONTENT = "GET_CONTENT";
 export const ACTION_SUMMARIZE = "ACTION_SUMMARIZE";