feat: support multiple image uploads for AI event generation 🖼️

- Updated OpenRouter integration to accept an array of image URLs
- Updated ImagePicker to use the `multiple` attribute natively
- Added `appendImagesDeduped` for handling client-side image deduplication
- Enhanced clipboard pasting to extract multiple images at once
- Rendered multiple images in a horizontal thumbnail strip in the AIToolbar
- Added tests to cover multi-image logic and AI request mapping

src/app/api/ai-event/route.ts

@@ -1,6 +1,7 @@
 import { headers } from "next/headers";
 import { NextResponse } from "next/server";
 import { auth } from "@/auth";
+import { buildMultimodalMessages } from "@/lib/ai-event-messages";
 import { extractJsonFromText } from "@/lib/json-utils";
 import { openRouterClient } from "@/lib/openrouter-client";
 import { AiEventRequestSchema, AiEventResponseSchema } from "@/lib/types";
@@ -31,7 +32,8 @@ Rules:
   - If no end time is given (and event is not allDay), default to 1 hour after start.
   - If multiple events are described, return multiple.
   - If recurrence is implied (e.g. "every Monday", "daily for 10 days", "monthly on the 15th"), generate a recurrenceRule.
-  - When analyzing an image, extract ALL visible event details: titles, dates, times, locations, descriptions.
+  - When analyzing images, extract ALL visible event details: titles, dates, times, locations, descriptions.
+  - If multiple images are provided, treat them all as sources for events (e.g. multiple flyer pages).
   - Output ONLY valid JSON (no prose).
 `;
 
@@ -68,27 +70,9 @@ const extractContentFromChatResponse = (response: unknown): string => {
 const callMultimodal = async (
 	systemPrompt: string,
 	prompt: string | undefined,
-	imageBase64: string,
+	images: string[],
 ) => {
-	const messages = [
-		{
-			role: "system" as const,
-			content: systemPrompt,
-		},
-		{
-			role: "user" as const,
-			content: [
-				{
-					type: "text" as const,
-					text: prompt || "Extract all calendar events from this image.",
-				},
-				{
-					type: "image_url" as const,
-					imageUrl: { url: imageBase64 },
-				},
-			],
-		},
-	];
+	const messages = buildMultimodalMessages(systemPrompt, prompt, images);
 
 	const response = await openRouterClient.chat.send({
 		chatRequest: {
@@ -126,13 +110,14 @@ export async function POST(request: Request) {
 		);
 	}
 
-	const { prompt, imageBase64 } = parsedInput.data;
+	const { prompt, images } = parsedInput.data;
 	const systemPrompt = buildSystemPrompt();
 
 	try {
-		const result = imageBase64
-			? await callMultimodal(systemPrompt, prompt, imageBase64)
-			: await callTextOnly(systemPrompt, prompt ?? "");
+		const result =
+			images && images.length > 0
+				? await callMultimodal(systemPrompt, prompt, images)
+				: await callTextOnly(systemPrompt, prompt ?? "");
 
 		const rawJson = extractJsonFromText(result.rawResponse);
 		const validated = AiEventResponseSchema.safeParse(rawJson);