chore(harness): quietStartup + project-local trust for clean RPC spawn

Set quietStartup:true in .pi/settings.json to suppress Pi banner on RPC stdout.
Add test pinning both quietStartup and theme values. Document project-local trust
requirement (--approve) so no trust prompt blocks RPC loop iteration.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

harness/.pi/extensions/gate/__tests__/settings.test.js

@@ -0,0 +1,10 @@
+const test = require("node:test");
+const assert = require("node:assert");
+const fs = require("node:fs");
+const path = require("node:path");
+
+test("settings.json abilita quietStartup", () => {
+  const s = JSON.parse(fs.readFileSync(path.join(__dirname, "../../../settings.json"), "utf8"));
+  assert.equal(s.quietStartup, true);
+  assert.equal(s.theme, "thothii-mono");
+});