fix: detect models that don't support image input and return clear error

Some models (Kimi K2, DeepSeek, Qwen text models) don't support image/vision
input. The AI SDK silently drops unsupported image parts, causing confusing
responses where the model acts as if no image was uploaded.

Added supportsImageInput() function to detect unsupported models by name,
and return a 400 error with clear guidance when users try to upload images
to these models.

Closes #469

packages/mcp-server/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@next-ai-drawio/mcp-server",
-    "version": "0.1.11",
+    "version": "0.1.10",
     "description": "MCP server for Next AI Draw.io - AI-powered diagram generation with real-time browser preview",
     "type": "module",
     "main": "dist/index.js",

packages/mcp-server/src/http-server.ts

@@ -127,12 +127,7 @@ function cleanupExpiredSessions(): void {
     }
 }
 
-const cleanupIntervalId = setInterval(cleanupExpiredSessions, 5 * 60 * 1000)
+setInterval(cleanupExpiredSessions, 5 * 60 * 1000)
-
-export function shutdown(): void {
-    clearInterval(cleanupIntervalId)
-    stopHttpServer()
-}
 
 export function getServerPort(): number {
     return serverPort

packages/mcp-server/src/index.ts

@@ -39,7 +39,6 @@ import {
     getState,
     requestSync,
     setState,
-    shutdown,
     startHttpServer,
     waitForSync,
 } from "./http-server.js"
@@ -619,31 +618,6 @@ server.registerTool(
     },
 )
 
-// Graceful shutdown handler
-let isShuttingDown = false
-function gracefulShutdown(reason: string) {
-    if (isShuttingDown) return
-    isShuttingDown = true
-    log.info(`Shutting down: ${reason}`)
-    shutdown()
-    process.exit(0)
-}
-
-// Handle stdin close (primary method - works on all platforms including Windows)
-process.stdin.on("close", () => gracefulShutdown("stdin closed"))
-process.stdin.on("end", () => gracefulShutdown("stdin ended"))
-
-// Handle signals (may not work reliably on Windows)
-process.on("SIGINT", () => gracefulShutdown("SIGINT"))
-process.on("SIGTERM", () => gracefulShutdown("SIGTERM"))
-
-// Handle broken pipe (writing to closed stdout)
-process.stdout.on("error", (err) => {
-    if (err.code === "EPIPE" || err.code === "ERR_STREAM_DESTROYED") {
-        gracefulShutdown("stdout error")
-    }
-})
-
 // Start the MCP server
 async function main() {
     log.info("Starting MCP server for Next AI Draw.io (embedded mode)...")