feat: add InputHalo landing page with DMG download flow

Add a marketing landing page for inputhalo.freno.me with a hero section
(theme-aware app icon, glitch title, tagline), feature highlights, and a
download section offering a macOS DMG via the tRPC signed-S3 URL endpoint
plus an App Store link.

Extract the download orchestration into a pure, side-effect-free helper
(query/performInputHaloDownload) so the asset-name and redirect contract is
unit-tested in isolation, mirroring the existing site-aware page-head /
nav-config split. Include dark and default app-icon exports in the public
folder.

src/routes/inputhalo/download.test.ts

@@ -0,0 +1,145 @@
+/**
+ * Unit tests for the InputHalo landing-page download flow (task 06).
+ *
+ * The helper in `./download.ts` is pure (no solid-js / router / meta imports),
+ * so we exercise the acceptance criterion directly — "the download button
+ * calls `api.downloads.getDownloadUrl` with `'inputhalo'` and redirects to the
+ * signed S3 URL" — without a DOM.
+ *
+ * Integration / visual checks (the rendered landing page, the tRPC client) are
+ * covered by the build gate (`bun run build`) and the manual validation steps
+ * in the task spec; the component is a thin wrapper over this helper.
+ */
+import { describe, it, expect, mock } from "bun:test";
+import {
+  INPUTHALO_APP_STORE_URL,
+  INPUTHALO_ASSET_NAME,
+  INPUTHALO_ICON_DARK,
+  INPUTHALO_ICON_DEFAULT,
+  INPUTHALO_MIN_SYSTEM_VERSION,
+  performInputHaloDownload,
+  queryInputHaloDownload,
+  type DownloadQueryApi
+} from "./download";
+
+describe("InputHalo download constants", () => {
+  it("asset name is 'inputhalo' (matches downloads.tsx)", () => {
+    expect(INPUTHALO_ASSET_NAME).toBe("inputhalo");
+  });
+
+  it("app store URL points at the InputHalo listing", () => {
+    expect(INPUTHALO_APP_STORE_URL).toBe(
+      "https://apps.apple.com/us/app/inputhalo/"
+    );
+  });
+
+  it("minimum system version is 14.6 (per Info.plist)", () => {
+    expect(INPUTHALO_MIN_SYSTEM_VERSION).toBe("14.6");
+  });
+
+  it("icons resolve from the 'InputHalo Exports' subfolder (Gaze pattern)", () => {
+    expect(INPUTHALO_ICON_DARK).toBe(
+      "/InputHalo Exports/InputHalo-iOS-Dark-1024x1024@1x.png"
+    );
+    expect(INPUTHALO_ICON_DEFAULT).toBe(
+      "/InputHalo Exports/InputHalo-iOS-Default-1024x1024@1x.png"
+    );
+  });
+});
+
+describe("queryInputHaloDownload", () => {
+  it("calls the query with asset_name 'inputhalo' and returns the signed URL", async () => {
+    const query = mock(
+      (async (input: { asset_name: string }) => {
+        expect(input.asset_name).toBe("inputhalo");
+        return { downloadURL: "https://s3.example.com/InputHalo.dmg?signed=1" };
+      }) as DownloadQueryApi
+    );
+
+    const url = await queryInputHaloDownload(query);
+
+    expect(query).toHaveBeenCalledTimes(1);
+    expect(url).toBe("https://s3.example.com/InputHalo.dmg?signed=1");
+  });
+
+  it("propagates the exact asset name 'inputhalo' (spelled correctly)", async () => {
+    let captured: string | undefined;
+    const query: DownloadQueryApi = async (input) => {
+      captured = input.asset_name;
+      return { downloadURL: "https://example.com/x.dmg" };
+    };
+    await queryInputHaloDownload(query);
+    expect(captured).toBe("inputhalo");
+  });
+
+  it("propagates query rejection", async () => {
+    const boom = new Error("S3 unreachable");
+    const query: DownloadQueryApi = async () => {
+      throw boom;
+    };
+    await expect(queryInputHaloDownload(query)).rejects.toThrow(boom);
+  });
+});
+
+describe("performInputHaloDownload", () => {
+  const SIGNED_URL = "https://s3.example.com/InputHalo-0.1.0.dmg?sig=abc";
+
+  it("redirects to the signed S3 URL returned by the query", async () => {
+    const query = mock(
+      (async () => ({ downloadURL: SIGNED_URL })) as DownloadQueryApi
+    );
+    const redirect = mock((url: string) => url);
+
+    const ok = await performInputHaloDownload(query, redirect);
+
+    expect(ok).toBe(true);
+    expect(query).toHaveBeenCalledTimes(1);
+    expect(redirect).toHaveBeenCalledTimes(1);
+    expect(redirect).toHaveBeenCalledWith(SIGNED_URL);
+  });
+
+  it("queries the tRPC endpoint with asset_name 'inputhalo'", async () => {
+    const seen: { asset_name: string }[] = [];
+    const query: DownloadQueryApi = async (input) => {
+      seen.push(input);
+      return { downloadURL: SIGNED_URL };
+    };
+    const redirect = mock((_url: string) => {});
+
+    await performInputHaloDownload(query, redirect);
+
+    expect(seen).toEqual([{ asset_name: "inputhalo" }]);
+  });
+
+  it("does not redirect when the query rejects", async () => {
+    const query: DownloadQueryApi = async () => {
+      throw new Error("network down");
+    };
+    const redirect = mock((_url: string) => {});
+    const onError = mock((_: unknown) => {});
+
+    const ok = await performInputHaloDownload(query, redirect, onError);
+
+    expect(ok).toBe(false);
+    expect(redirect).not.toHaveBeenCalled();
+    expect(onError).toHaveBeenCalledTimes(1);
+  });
+
+  it("defaults the error sink to console.error", async () => {
+    const original = console.error;
+    const seen: unknown[] = [];
+    console.error = (...args: unknown[]) => seen.push(args);
+
+    const query: DownloadQueryApi = async () => {
+      throw new Error("boom");
+    };
+
+    try {
+      const ok = await performInputHaloDownload(query, () => {});
+      expect(ok).toBe(false);
+      expect(seen.length).toBeGreaterThanOrEqual(1);
+    } finally {
+      console.error = original;
+    }
+  });
+});