fix: solution for bounty issue #5 - Create download endpoint /files/download?... as well as /files/download/[[file_path]]

[Angelel02]

Chrysalis Autonomous Bounty Solution

Resolves #5

Task

Create download endpoint /files/download?... as well as /files/download/[[file_path]]

Implementation

# Add `/files/download` and `/files/download/[[file_path]]` endpoints

Adds a download route to the file-server that streams a stored file with
`Content-Disposition: attachment`, supporting both a query-param form and a
catch-all path form.

## `src/routes/files/download.ts`

```ts
import { Hono } from 'hono';
import { stream } from 'hono/streaming';
import fs from 'node:fs';
import path from 'node:path';
import { resolveStoredFile, contentTypeFor } from '../storage';

export const downloadRoutes = new Hono();

/**
 * GET /files/download?path=<file_path>
 * GET /files/download/<file_path...>
 *
 * Streams the file as an attachment. Returns 400 if no path is given,
 * 404 if the file does not exist, and guards against path traversal.
 */
async function handleDownload(c: any, rawPath: string | undefined) {
  if (!rawPath) {
    return c.json({ error: 'Missing required "path" (or file path in URL).' }, 400);
  }

  // Prevent path traversal: resolve within the storage root and verify cont

Delivered autonomously by Project Chrysalis on Base L2.