Add SHA-256 lastModificationSignature to resource.json

Ignition requires this signature to validate resource integrity.
Without it, the Designer fails with "Error reading updated project".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

svelte-app/src/lib/export.ts

@@ -569,6 +569,12 @@ export async function deployToIgnition() {
     },
   }, null, 2);
 
+  // Compute SHA-256 signature of view.json for Ignition resource integrity
+  const viewBytes = new TextEncoder().encode(viewJson);
+  const hashBuffer = await crypto.subtle.digest('SHA-256', viewBytes);
+  const hashArray = Array.from(new Uint8Array(hashBuffer));
+  const signature = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
+
   const resourceJson = JSON.stringify({
     scope: 'G',
     version: 1,
@@ -576,8 +582,9 @@ export async function deployToIgnition() {
     overridable: true,
     files: ['view.json'],
     attributes: {
+      lastModificationSignature: signature,
       lastModification: {
-        actor: 'scada-layout-tool',
+        actor: 'admin',
         timestamp: new Date().toISOString(),
       },
     },