fix(signing): add minimal signer tsconfig/src to satisfy Docker COPY; allow full rebuild

modules/sdk_signer/src/index.ts

@@ -0,0 +1,6 @@
+export function sdkSignerInit(): void {
+  // Minimal placeholder to satisfy build during initial integration
+}
+
+export default sdkSignerInit;
+

modules/sdk_signer/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "ES2019",
+    "module": "commonjs",
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "esModuleInterop": true,
+    "strict": false
+  },
+  "include": ["src/**/*"]
+}
+