chore: keep the internal view id out of the release banner (closes #375)

The debug/testnet banner appended the active view's internal id, so the
user saw text like "[TESTNET] (approve-tx)" — developer vocabulary, and on
the approval screen it sat directly above the carefully worded line stating
what is being authorized. The view id is now gated on the compile-time
DEBUG constant instead of isDebug(), so it survives only in a debug build.
A testnet or the runtime debug toggle still raises the banner, but without
the view id, which is what a release build shows.

Model: opus-4-8

tests/debugBanner.test.js

@@ -0,0 +1,59 @@
+// Tests for the debug/testnet banner (issue #375).
+//
+// On a testnet the banner is raised even in a release build, but it must not
+// append the active view's internal id: the user should see "[TESTNET]", never
+// "[TESTNET] (approve-tx)". The suffix is gated on the compile-time DEBUG
+// constant, which is false in a plain test load, so this drives exactly the
+// text a shipped build renders. Revert the gate to the old unconditional
+// suffix and this fails.
+//
+// The banner is created on demand by updateDebugBanner(); the document stub
+// records what it prepends so the assertion can read the resulting text.
+
+function makeBanner() {
+    return {
+        id: "",
+        textContent: "",
+        style: { cssText: "" },
+        remove() {},
+    };
+}
+
+function makeDocument() {
+    let banner = null;
+    return {
+        getElementById(id) {
+            return id === "debug-banner" ? banner : null;
+        },
+        createElement: () => makeBanner(),
+        body: {
+            prepend(node) {
+                banner = node;
+            },
+        },
+    };
+}
+
+function load() {
+    jest.resetModules();
+    globalThis.chrome = {
+        storage: { local: { get: async () => ({}), set: async () => {} } },
+    };
+    globalThis.document = makeDocument();
+    const helpers = require("../src/popup/views/helpers");
+    const { state } = require("../src/shared/state");
+    return { helpers, state };
+}
+
+describe("the release banner on a testnet", () => {
+    test("carries no internal view id", () => {
+        const { helpers, state } = load();
+        state.networkId = "sepolia";
+
+        helpers.updateDebugBanner("approve-tx");
+
+        expect(
+            globalThis.document.getElementById("debug-banner").textContent,
+        ).toBe("[TESTNET]");
+    });
+});