Remove contextMode, consolidate wake policies, and default serveUi to true

Drop the unused contextMode field from the agent schema, shared types, validators,
and all UI references. Merge wakeOnOnDemand and wakeOnAutomation into a single
wakeOnDemand toggle. Default serveUi to true and remove the onboarding prompt for it.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/shared/src/validators/agent.ts

@@ -1,7 +1,6 @@
 import { z } from "zod";
 import {
   AGENT_ADAPTER_TYPES,
-  AGENT_CONTEXT_MODES,
   AGENT_ROLES,
   AGENT_STATUSES,
 } from "../constants.js";
@@ -15,7 +14,6 @@ export const createAgentSchema = z.object({
   adapterType: z.enum(AGENT_ADAPTER_TYPES).optional().default("process"),
   adapterConfig: z.record(z.unknown()).optional().default({}),
   runtimeConfig: z.record(z.unknown()).optional().default({}),
-  contextMode: z.enum(AGENT_CONTEXT_MODES).optional().default("thin"),
   budgetMonthlyCents: z.number().int().nonnegative().optional().default(0),
   metadata: z.record(z.unknown()).optional().nullable(),
 });