feat(FN-3160): move roadmap route context into fusion-plugin-roadmap plugin

The merge completes FN-3160 by making the roadmap route context plugin-owned, moving `roadmap-routes` and `roadmap-suggestions` logic from the dashboard into `fusion-plugin-roadmap` with updated plugin-loader integration. It also includes FN-3755's shared state snapshot support for mesh sync hardeni

Fusion-Task-Id: FN-3160

packages/core/src/__tests__/plugin-loader.route-context.test.ts

@@ -0,0 +1,22 @@
+import { describe, it, expect, vi } from "vitest";
+import { PluginLoader } from "../plugin-loader.js";
+
+describe("PluginLoader.createRouteContext", () => {
+  it("applies overrides including resolveProjectTaskStore", async () => {
+    const pluginStore = {
+      getPlugin: vi.fn().mockResolvedValue({ settings: { x: 1 } }),
+    } as any;
+    const baseStore = { getRootDir: () => "/tmp" } as any;
+    const loader = new PluginLoader({ pluginStore, taskStore: baseStore });
+    const resolveProjectTaskStore = vi.fn();
+    const ctx = await loader.createRouteContext("roadmap-planner", {
+      taskStore: baseStore,
+      settings: { ok: true },
+      resolveProjectTaskStore,
+    });
+
+    expect(ctx.pluginId).toBe("roadmap-planner");
+    expect(ctx.settings).toEqual({ ok: true });
+    expect(ctx.resolveProjectTaskStore).toBe(resolveProjectTaskStore);
+  });
+});

packages/core/src/plugin-loader.ts

@@ -114,25 +114,32 @@ export class PluginLoader extends EventEmitter<{
   // ── Context Creation ───────────────────────────────────────────────
 
   private async createContext(plugin: FusionPlugin): Promise<PluginContext> {
+    return this.createRouteContext(plugin.manifest.id);
+  }
+
+  async createRouteContext(
+    pluginId: string,
+    overrides?: Partial<Pick<PluginContext, "taskStore" | "settings" | "resolveProjectTaskStore">>,
+  ): Promise<PluginContext> {
     const createAiSession = await getCreateAiSessionFactory();
     if (process.env.DEBUG?.includes("plugins")) {
       this.log.log(
         createAiSession
-          ? `[plugin:${plugin.manifest.id}] createAiSession available`
-          : `[plugin:${plugin.manifest.id}] createAiSession unavailable`,
+          ? `[plugin:${pluginId}] createAiSession available`
+          : `[plugin:${pluginId}] createAiSession unavailable`,
       );
     }
 
     return {
-      pluginId: plugin.manifest.id,
-      taskStore: this.options.taskStore,
-      settings: await this.getPluginSettings(plugin.manifest.id),
-      logger: this.createLogger(plugin.manifest.id),
+      pluginId,
+      taskStore: overrides?.taskStore ?? this.options.taskStore,
+      settings: overrides?.settings ?? await this.getPluginSettings(pluginId),
+      logger: this.createLogger(pluginId),
       createAiSession,
+      resolveProjectTaskStore: overrides?.resolveProjectTaskStore,
       emitEvent: (event: string, data: unknown) => {
-        this.emit("plugin:error", { pluginId: plugin.manifest.id, error: new Error(`Custom event: ${event}`) });
-        // Custom events are logged but not surfaced as errors
-        this.log.log(`[plugin:${plugin.manifest.id}] Custom event: ${event}`, data);
+        this.emit("plugin:error", { pluginId, error: new Error(`Custom event: ${event}`) });
+        this.log.log(`[plugin:${pluginId}] Custom event: ${event}`, data);
       },
     };
   }

packages/core/src/plugin-types.ts

@@ -137,6 +137,8 @@ export interface PluginContext {
   emitEvent: (event: string, data: unknown) => void;
   /** Engine-injected AI session factory (undefined when engine is not loaded) */
   createAiSession?: CreateAiSessionFactory;
+  /** Optional host capability to resolve a project-scoped TaskStore by projectId. */
+  resolveProjectTaskStore?: (projectId: string) => Promise<TaskStore>;
 }
 
 /**