Dockerfile: simplify - clone emdash source, build all packages, copy with -L flag

Changes:
- Build all packages (core, auth, blocks, admin) from source
- Copy packages with -L dereferencing symlinks so deps resolve properly
- Use emdash@0.9.0 from npm (source packages include their own deps)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -18,13 +18,18 @@
 	"dependencies": {
 		"@astrojs/node": "^10.0.0",
 		"@astrojs/react": "^5.0.0",
+		"@emdash-cms/admin": "^0.9.0",
 		"@emdash-cms/plugin-audit-log": "^0.1.1",
+		"@lingui/react": "^5.9.4",
 		"astro": "^6.0.1",
 		"better-sqlite3": "^12.8.0",
-		"emdash": "^0.8.0",
+		"emdash": "^0.9.0",
 		"kysely": "^0.27.0",
 		"react": "19.2.4",
-		"react-dom": "19.2.4"
+		"react-dom": "19.2.4",
+		"react-hotkeys-hook": "^5.2.4",
+		"dompurify": "^3.3.2",
+		"marked": "^17.0.3"
 	},
 	"devDependencies": {
 		"@astrojs/check": "^0.9.7"