feat(agent): support Responses steering and project-aware tools

Use the dedicated TJWATER_AGENT_URL and Responses stream protocol. Keep running
turns active while users steer or queue follow-ups and edit pending delivery.
Refresh the model catalog before generation and preserve approval mode selection.

Integrate scoped investigation messaging/presentation, geographic place selection,
current Agent composer styles and supporting workbench contracts.

Validation: 77 focused Vitest checks, 21 browser cases, lint, typecheck and
production build. Preserve direct Server/Agent routing and project authentication.

tests/browser/palette.e2e.ts

@@ -25,11 +25,9 @@ test("gem-blue actions and semantic labels remain readable on the new surfaces",
   expect(tint[2]).toBeGreaterThan(tint[1]);
   expect(tint[2]).toBeGreaterThan(tint[0]);
   await expectThemeColor(panel.locator("form.agent-panel-control"), "background-color", "--surface-reading");
-  const body = panel.getByText("直接说出你想调查的问题，我会整理监测与空间证据，并将分析结果带回地图。");
-  expect(await readRenderedContrast(body)).toBeGreaterThanOrEqual(4.5);
   expect(await readRenderedContrast(panel.getByText("对话主题"))).toBeGreaterThanOrEqual(4.5);
 
-  await page.getByPlaceholder("输入调度问题，Agent 将通过后端会话流式响应").fill("检查压力变化");
+  await page.getByPlaceholder("询问供水问题，或描述需要处理的任务").fill("检查压力变化");
   const send = panel.getByRole("button", { name: "发送 Agent 指令", exact: true });
   await expect(send).toBeEnabled();
   await expectThemeColor(send, "background-color", "--action-blue");