downloads: track every door and surface them on /analytics

The analytics page could not answer "how many downloads, of which
product". Three of the four download doors recorded nothing: the tRPC
click proxy only left the generic request row, whose path is the raw URL
with the asset buried in `?batch=1&input={"asset_name":...}`, and the S3
file route that serves Sparkle updates and the Nook app logged nothing
at all. The one door that did log (the Nook redirect) kept a private copy
of the logVisit/enrich/flush sequence, under its own path.

All doors now go through trackDownload, which writes one row per event
under /api/downloads/<asset> and flushes it inside the request — a click
is low-volume and serverless is not guaranteed to run the 30s batch
timer after the response. The file route maps its prefix allowlist to
asset keys, so a version bump stays one asset rather than one per
release. getAnalyticsSummary groups those rows into a downloads block and
the freno.me panel renders it under the overview cards.

History is recovered to the degree it exists: the Nook door's rows and
the tRPC clicks still carry enough to derive from (asset name in the URL).
scripts/backfill-downloads.ts inserts those derived rows with a
`backfill-<source id>` primary key and INSERT OR IGNORE, leaving the
originals untouched, so re-running is a no-op. Run against the live table
it added 66 rows: gaze 42, thenook 19, inputhalo 4, lineage 1.

Tests: new backfill suite (derivation, visitor detail carried over,
idempotency, empty history) and summariseDownloads cases; the Nook route
test now pins the canonical path, and the NOOK-337 allowlist audit reads
the map keys instead of quoted strings. Red-checked by stubbing the
downloads block back to zeros — the summary case fails, then passes.
Full suite matches master.

Co-Authored-By: nw-flash <noreply@nw-flash.local>
MISC-48

src/routes/api/downloads/[filename].ts

@@ -1,6 +1,7 @@
 import type { APIEvent } from "@solidjs/start/server";
 import { S3Client, GetObjectCommand } from "@aws-sdk/client-s3";
 import { env } from "~/env/server";
+import { trackDownload } from "~/server/track-download";
 
 /**
  * Serves macOS app DMG files and delta updates from S3
@@ -27,10 +28,20 @@ export async function GET(event: APIEvent) {
     });
   }
 
-  const validPrefixes = ["Gaze", "InputHalo", "TheNook", "Nook"];
-  const isValidPrefix = validPrefixes.some((prefix) => filename.startsWith(prefix));
+  // Prefix → canonical asset key, so a version bump stays one asset in
+  // analytics rather than one per release.
+  const assetKeys: Record<string, string> = {
+    Gaze: "gaze",
+    InputHalo: "inputhalo",
+    TheNook: "thenook",
+    Nook: "thenook"
+  };
+
+  const asset = Object.keys(assetKeys).find((prefix) =>
+    filename.startsWith(prefix)
+  );
   if (
-    !isValidPrefix ||
+    !asset ||
     (!filename.endsWith(".dmg") &&
       !filename.endsWith(".delta") &&
       !filename.endsWith(".zip"))
@@ -84,13 +95,20 @@ export async function GET(event: APIEvent) {
 
     console.log(`✓ Serving ${filename} (${body.length} bytes)`);
 
-    return new Response(body, {
+    await trackDownload(event, assetKeys[asset]!);
+
+    // SAFETY: `transformToByteArray` yields `Uint8Array<ArrayBufferLike>`, which the
+    // DOM lib's `BufferSource` (ArrayBuffer-backed) does not accept, though undici
+    // takes it as-is at runtime. State the intent at the one boundary it hits.
+    return new Response(body as unknown as BodyInit, {
       status: 200,
       headers: {
         "Content-Type": contentType,
         "Content-Length": body.length.toString(),
         "Content-Disposition": `attachment; filename="${filename}"`,
         "Cache-Control": "public, max-age=86400", // Cache for 24 hours
+        // Deliberately open: these are public installer files with no cookies or
+        // credentials, fetched by Sparkle and by direct browser navigation.
         "Access-Control-Allow-Origin": "*"
       }
     });