chore: prepare production deploy with API hardening and Railway adapter

* Harden API routes with rate limits, upload cap, and edit dedupe.

Protect expensive endpoints from abuse, reject oversized mood uploads, dedupe concurrent edit-images calls, and surface Kakao search failures instead of silent mock fallback.

Co-authored-by: Cursor <cursoragent@cursor.com>

* chore: switch to adapter-node for Railway deploy

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -6,6 +6,7 @@
 	"scripts": {
 		"dev": "vite dev",
 		"build": "vite build",
+		"start": "node build",
 		"preview": "vite preview",
 		"prepare": "svelte-kit sync || echo ''",
 		"lint": "prettier --check . && eslint .",
@@ -15,7 +16,6 @@
 	"devDependencies": {
 		"@eslint/compat": "^2.0.4",
 		"@eslint/js": "^10.0.1",
-		"@sveltejs/adapter-auto": "^7.0.1",
 		"@sveltejs/kit": "^2.57.0",
 		"@sveltejs/vite-plugin-svelte": "^7.0.0",
 		"@tailwindcss/vite": "^4.2.2",
@@ -34,6 +34,7 @@
 	"dependencies": {
 		"@google/generative-ai": "^0.24.1",
 		"@supabase/supabase-js": "^2.108.1",
+		"@sveltejs/adapter-node": "^5.5.4",
 		"openai": "^6.42.0",
 		"p5": "^2.3.0"
 	}