feat(plugin): provider plugins declare option controls and receive option changes

A provider plugin reports `controls` and the `providerOptions` it runs in
`session.config`, and receives running-session changes as
`session.configure` `changes.providerOptions` (null returns a key to its
default), under the same apply-or-throw contract as built-in providers.
A control may declare a `defaultValue`; a value a plugin reports at that
default for a key nobody set stays unset instead of being pinned to the agent.

A plugin that still reports `settings` keeps working: the daemon reads each
setting as a control plus an option and sends changes in both shapes
(COMPAT(plugin-provider-settings)).

The app resolves a control's icon as a Lucide name when it is not one of the
built-in kebab-case names, so a plugin's icon shows live and in drafts.
Public docs and the provider-direct example use only `providerOptions` and
controls; the migration doc gains the rows.

packages/app/src/agent-controls/icons.test.ts

@@ -0,0 +1,16 @@
+import { Settings2 } from "lucide-react-native";
+import { describe, expect, it } from "vitest";
+import { getAgentFeatureIcon } from "./icons";
+
+describe("getAgentFeatureIcon", () => {
+  it("draws the Lucide icon a plugin provider names", () => {
+    const icon = getAgentFeatureIcon("Mic");
+    expect(icon).not.toBe(Settings2);
+    expect(getAgentFeatureIcon("Mic")).toBe(icon);
+  });
+
+  it("falls back to the generic icon for a missing or unknown name", () => {
+    expect(getAgentFeatureIcon()).toBe(Settings2);
+    expect(getAgentFeatureIcon("not-an-icon")).toBe(Settings2);
+  });
+});

packages/app/src/agent-controls/icons.ts

@@ -13,6 +13,7 @@ import {
   ShieldQuestionMark,
   Zap,
 } from "lucide-react-native";
+import { isLucideIconName, pluginIconComponent } from "@/plugins/icons";
 import { getModeVisuals, type AgentProviderDefinition } from "@getpaseo/protocol/provider-manifest";
 
 export interface AgentControlIconProps {
@@ -60,6 +61,9 @@ export function getAgentModeOptionIcon(
   return icon ? MODE_ICONS[icon] : undefined;
 }
 
+/** A built-in control names its icon in kebab case; a plugin provider names a Lucide icon. */
 export function getAgentFeatureIcon(icon?: string): AgentControlIcon {
-  return (icon ? FEATURE_ICONS[icon] : undefined) ?? Settings2;
+  if (!icon) return Settings2;
+  if (FEATURE_ICONS[icon]) return FEATURE_ICONS[icon];
+  return isLucideIconName(icon) ? pluginIconComponent(icon) : Settings2;
 }

packages/app/src/plugins/icons.ts

@@ -25,6 +25,11 @@ function findLucideIcon(name: string): LucideIcon | null {
   return isComponent(candidate) ? (candidate as LucideIcon) : null;
 }
 
+/** Whether `name` is a Lucide icon, so a caller can fall back before drawing nothing. */
+export function isLucideIconName(name: string): boolean {
+  return findLucideIcon(name) !== null;
+}
+
 function isComponent(value: unknown): boolean {
   return (
     typeof value === "function" ||