feat(FN-3159): move roadmap ownership from core to fusion-plugin-roadmap pl

Moves roadmap ownership from `@fusion/core` to `fusion-plugin-roadmap`, deleting ~1,800 lines of roadmap store, types, ordering, and handoff logic from core and replacing it with ~760 lines of new route handlers in the plugin. The dashboard's roadmap routes and suggestions modules are substantially

Fusion-Task-Id: FN-3159

plugins/fusion-plugin-roadmap/package.json

@@ -10,12 +10,16 @@
       "import": "./src/index.ts"
     },
     "./server": {
-      "types": "./src/server/index.ts",
+      "types": "./src/server/index.d.ts",
       "import": "./src/server/index.ts"
     },
     "./dashboard-view": {
       "types": "./src/dashboard-view.ts",
       "import": "./src/dashboard-view.ts"
+    },
+    "./roadmap-suggestions": {
+      "types": "./src/roadmap-suggestions.d.ts",
+      "import": "./src/roadmap-suggestions.ts"
     }
   },
   "scripts": {
@@ -29,6 +33,7 @@
     "express": "^5.1.0"
   },
   "devDependencies": {
+    "@types/express": "^5.0.5",
     "@types/node": "^25.5.2",
     "typescript": "^5.7.0",
     "vitest": "^3.2.4"