feat(FN-3803): add universal web fetch to reviewer, merger, and triage agen

The merge introduces the universal web fetch tool across reviewer/merger/triage agents (FN-3803, 4 commits) with docs and regression test, extracts the roadmap as a plugin scaffold in `plugins/fusion-plugin-reports` (FN-3166, FN-3165) while removing dashboard roadmap backend and associated tests, ad

Fusion-Task-Id: FN-3803

packages/engine/src/triage.ts

@@ -52,6 +52,7 @@ import {
   createListAgentsTool,
   createMemoryTools,
   createResearchTools,
+  createWebFetchTool,
   createTaskDocumentReadTool,
   createTaskDocumentWriteTool,
 } from "./agent-tools.js";
@@ -966,6 +967,7 @@ export class TriageProcessor {
               },
             }
             : undefined),
+          createWebFetchTool(),
           // Agent delegation tools — discover and delegate work to other agents.
           ...(this.options.agentStore ? [
             createListAgentsTool(this.options.agentStore),