Add EmDash CMS blog + hero standardization + seed fix

- Add EmDash CMS integration with SQLite and local storage
- Add blog collection (seed/seed.json) with 3 sample posts
- Add /บทความ list page and /บทความ/[slug] detail page
- Add blog section to homepage
- Fix reserved field slugs (slug, published_at removed from fields)
- Fix date field mapping (publishedAt camelCase)
- Fix featured image URL for admin-uploaded images (meta.storageKey)
- Standardize all product page hero sections
- Update navigation with 'บทความ' link
- Configure Google OAuth provider

astro.config.mjs

@@ -1,5 +1,10 @@
 import { defineConfig } from 'astro/config'
 import tailwindcss from '@tailwindcss/vite'
+import node from '@astrojs/node'
+import react from '@astrojs/react'
+import emdash, { local } from 'emdash/astro'
+import { sqlite } from 'emdash/db'
+import { google } from 'emdash/auth/providers/google'
 import { fileURLToPath } from 'url'
 import path from 'path'
 
@@ -7,6 +12,10 @@ const __dirname = path.dirname(fileURLToPath(import.meta.url))
 
 export default defineConfig({
   site: 'https://dealplustech.com',
+  output: 'server',
+  adapter: node({
+    mode: 'standalone',
+  }),
   vite: {
     plugins: [tailwindcss()],
     resolve: {
@@ -18,7 +27,17 @@ export default defineConfig({
       },
     },
   },
-  output: 'static',
+  integrations: [
+    react(),
+    emdash({
+      database: sqlite({ url: 'file:./data.db' }),
+      storage: local({
+        directory: './uploads',
+        baseUrl: '/_emdash/api/media/file',
+      }),
+      authProviders: [google()],
+    }),
+  ],
   build: {
     assets: '_assets',
   },
@@ -26,4 +45,5 @@ export default defineConfig({
     host: '0.0.0.0',
     port: 3100,
   },
+  devToolbar: { enabled: false },
 })