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>

ui/src/components/AgentConfigForm.tsx

@@ -642,34 +642,14 @@ export function AgentConfigForm(props: AgentConfigFormProps) {
                 Advanced
               </div>
               <ToggleField
-                label="Wake on assignment"
-                hint={help.wakeOnAssignment}
+                label="Wake on demand"
+                hint={help.wakeOnDemand}
                 checked={eff(
                   "heartbeat",
-                  "wakeOnAssignment",
-                  heartbeat.wakeOnAssignment !== false,
+                  "wakeOnDemand",
+                  heartbeat.wakeOnDemand !== false,
                 )}
-                onChange={(v) => mark("heartbeat", "wakeOnAssignment", v)}
-              />
-              <ToggleField
-                label="Wake on on-demand"
-                hint={help.wakeOnOnDemand}
-                checked={eff(
-                  "heartbeat",
-                  "wakeOnOnDemand",
-                  heartbeat.wakeOnOnDemand !== false,
-                )}
-                onChange={(v) => mark("heartbeat", "wakeOnOnDemand", v)}
-              />
-              <ToggleField
-                label="Wake on automation"
-                hint={help.wakeOnAutomation}
-                checked={eff(
-                  "heartbeat",
-                  "wakeOnAutomation",
-                  heartbeat.wakeOnAutomation !== false,
-                )}
-                onChange={(v) => mark("heartbeat", "wakeOnAutomation", v)}
+                onChange={(v) => mark("heartbeat", "wakeOnDemand", v)}
               />
               <Field label="Cooldown (sec)" hint={help.cooldownSec}>
                 <DraftNumberInput
@@ -693,11 +673,6 @@ export function AgentConfigForm(props: AgentConfigFormProps) {
         <div className="border-b border-border">
           <div className="px-4 py-2 text-xs font-medium text-muted-foreground">Runtime</div>
           <div className="px-4 pb-3 space-y-3">
-            <Field label="Context mode" hint={help.contextMode}>
-              <div className="text-sm font-mono px-2.5 py-1.5">
-                {props.agent.contextMode}
-              </div>
-            </Field>
             <Field label="Monthly budget (cents)" hint={help.budgetMonthlyCents}>
               <DraftNumberInput
                 value={eff(