Address workspace diff review findings

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/plugins/plugin-workspace-diff/src/manifest.ts

@@ -14,6 +14,7 @@ const manifest: PaperclipPluginManifestV1 = {
   capabilities: [
     "ui.detailTab.register",
     "execution.workspaces.read",
+    "project.workspaces.read",
   ],
   entrypoints: {
     worker: "./dist/worker.js",

packages/plugins/plugin-workspace-diff/tests/fixtures.ts

@@ -47,8 +47,6 @@ export function diffResponse(overrides: Partial<WorkspaceDiffResponse> = {}): Wo
   return {
     workspaceId: "11111111-1111-4111-8111-111111111111",
     companyId: "22222222-2222-4222-8222-222222222222",
-    repoRoot: "/tmp/paperclip",
-    cwd: "/tmp/paperclip",
     view: "working-tree",
     baseRef: null,
     headSha: null,

packages/plugins/plugin-workspace-diff/tests/plugin.spec.ts

@@ -8,6 +8,7 @@ describe("workspace diff plugin", () => {
   it("declares workspace Changes tabs and host diff capability", () => {
     expect(manifest.capabilities).toContain("ui.detailTab.register");
     expect(manifest.capabilities).toContain("execution.workspaces.read");
+    expect(manifest.capabilities).toContain("project.workspaces.read");
     expect(manifest.ui?.slots).toContainEqual(expect.objectContaining({
       type: "detailTab",
       displayName: "Changes",