feat(plugins): add local plugin surfaces and RPCs

Keep plugin execution scoped to its daemon while allowing one local TypeScript entry point to contribute validated RPCs and native client surfaces. Paseo owns host selection, navigation chrome, and per-installation query caches.

examples/local-plugin/index.tsx

@@ -0,0 +1,74 @@
+import React, { useCallback, useMemo } from "react";
+import { Pressable, Text, View } from "react-native";
+import { useMutation } from "@tanstack/react-query";
+import { z } from "zod";
+import { defineRpc, type PluginContext, useRpc } from "@paseo/plugin";
+
+const incrementRpc = defineRpc({
+  name: "increment",
+  input: z.object({ value: z.number() }),
+  output: z.object({ value: z.number(), handledBy: z.string() }),
+});
+
+interface ExampleTheme {
+  colors: {
+    surface0: string;
+    foreground: string;
+    foregroundMuted: string;
+    accent: string;
+    accentForeground: string;
+    statusDanger: string;
+  };
+}
+
+function ExampleSurface({ theme }: { theme: ExampleTheme }) {
+  const callIncrement = useRpc(incrementRpc);
+  const { data, error, isPending, mutate } = useMutation({ mutationFn: callIncrement });
+  const value = data?.value ?? 0;
+  const styles = useMemo(
+    () => ({
+      screen: { flex: 1, padding: 24, gap: 16, backgroundColor: theme.colors.surface0 },
+      title: { color: theme.colors.foreground, fontSize: 24 },
+      detail: { color: theme.colors.foregroundMuted },
+      button: { padding: 14, borderRadius: 10, backgroundColor: theme.colors.accent },
+      buttonText: { color: theme.colors.accentForeground, textAlign: "center" },
+      error: { color: theme.colors.statusDanger },
+    }),
+    [theme.colors],
+  );
+  const handleIncrement = useCallback(() => {
+    mutate({ value });
+  }, [mutate, value]);
+
+  return (
+    <View style={styles.screen}>
+      <Text style={styles.title}>Native plugin surface</Text>
+      <Text style={styles.detail}>{data?.handledBy ?? "The RPC has not run yet."}</Text>
+      <Pressable
+        accessibilityRole="button"
+        accessibilityLabel={`Increment plugin counter, currently ${value}`}
+        onPress={handleIncrement}
+        style={styles.button}
+      >
+        <Text style={styles.buttonText}>
+          {isPending ? "Calling daemon…" : `RPC counter: ${value}`}
+        </Text>
+      </Pressable>
+      {error ? <Text style={styles.error}>{error.message}</Text> : null}
+    </View>
+  );
+}
+
+export default function contribute(plugin: PluginContext) {
+  plugin.handle(incrementRpc, async (input) => ({
+    value: input.value + 1,
+    handledBy: "plugin subprocess",
+  }));
+  plugin.addSurface("main", ExampleSurface);
+  plugin.addSidebarItem({
+    id: "main",
+    title: "Local plugin",
+    icon: "Blocks",
+    surface: "main",
+  });
+}

examples/local-plugin/paseo-plugin.json

@@ -0,0 +1,3 @@
+{
+  "id": "local-example"
+}