Fix blank portal: add root element heights, use dagre for graph layout

- Set explicit height on html/body/#root so React Flow container renders
- Replace @dagrejs/dagre (broken CJS dynamic require) with dagre v0.8.5
- Hierarchical top-down layout with dagre, arrow markers on edges
- Move React Flow controls to top-right to avoid floating button overlap

portal/package-lock.json

@@ -9,7 +9,9 @@
       "version": "1.0.0",
       "dependencies": {
         "@tanstack/react-query": "^5.62.0",
+        "@types/dagre": "^0.7.53",
         "@xyflow/react": "^12.4.0",
+        "dagre": "^0.8.5",
         "react": "^19.0.0",
         "react-dom": "^19.0.0"
       },
@@ -1546,6 +1548,12 @@
         "@types/d3-selection": "*"
       }
     },
+    "node_modules/@types/dagre": {
+      "version": "0.7.53",
+      "resolved": "https://registry.npmjs.org/@types/dagre/-/dagre-0.7.53.tgz",
+      "integrity": "sha512-f4gkWqzPZvYmKhOsDnhq/R8mO4UMcKdxZo+i5SCkOU1wvGeHJeUXGIHeE9pnwGyPMDof1Vx5ZQo4nxpeg2TTVQ==",
+      "license": "MIT"
+    },
     "node_modules/@types/estree": {
       "version": "1.0.8",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.8.tgz",
@@ -1816,6 +1824,16 @@
         "node": ">=12"
       }
     },
+    "node_modules/dagre": {
+      "version": "0.8.5",
+      "resolved": "https://registry.npmjs.org/dagre/-/dagre-0.8.5.tgz",
+      "integrity": "sha512-/aTqmnRta7x7MCCpExk7HQL2O4owCT2h8NT//9I1OQ9vt29Pa0BzSAkR5lwFUcQ7491yVi/3CXU9jQ5o0Mn2Sw==",
+      "license": "MIT",
+      "dependencies": {
+        "graphlib": "^2.1.8",
+        "lodash": "^4.17.15"
+      }
+    },
     "node_modules/debug": {
       "version": "4.4.3",
       "resolved": "https://registry.npmjs.org/debug/-/debug-4.4.3.tgz",
@@ -1967,6 +1985,15 @@
       "dev": true,
       "license": "ISC"
     },
+    "node_modules/graphlib": {
+      "version": "2.1.8",
+      "resolved": "https://registry.npmjs.org/graphlib/-/graphlib-2.1.8.tgz",
+      "integrity": "sha512-jcLLfkpoVGmH7/InMC/1hIvOPSUh38oJtGhvrOFGzioE1DZ+0YW16RgmOJhHiuWTvGiJQ9Z1Ik43JvkRPRvE+A==",
+      "license": "MIT",
+      "dependencies": {
+        "lodash": "^4.17.15"
+      }
+    },
     "node_modules/jiti": {
       "version": "2.6.1",
       "resolved": "https://registry.npmjs.org/jiti/-/jiti-2.6.1.tgz",
@@ -2271,6 +2298,12 @@
         "url": "https://opencollective.com/parcel"
       }
     },
+    "node_modules/lodash": {
+      "version": "4.17.23",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.23.tgz",
+      "integrity": "sha512-LgVTMpQtIopCi79SJeDiP0TfWi5CNEc/L/aRdTh3yIvmZXTnheWpKjSZhnvMl8iXbC1tFg9gdHHDMLoV7CnG+w==",
+      "license": "MIT"
+    },
     "node_modules/lru-cache": {
       "version": "5.1.1",
       "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-5.1.1.tgz",