fix: resolve TypeScript import errors for download types module

### Changes:
- Moved types from legacy 'types/download.ts' to '@lib/download/types'
- Updated all imports to use the new location:
  - src/components/download/DownloadListingContent.tsx
  - src/components/download/FileTable.tsx
  - src/lib/download-data.ts
  - src/lib/download-manifest.ts
  - src/app/download/[...segments]/page.tsx

### Why:
- Resolved TS6137 error: Cannot import type declaration files
- Aligns with codebase pattern: types co-located with modules (@lib/iac/types, @lib/mail/types)
- Uses consistent @ alias import pattern throughout codebase

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

dashboard/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/types/routes.d.ts";
+import "./.next/dev/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.

dashboard/src/app/download/[...segments]/page.tsx

@@ -9,7 +9,7 @@ import {
   formatSegmentLabel,
 } from '../../../lib/download-data'
 import { DOWNLOAD_LISTINGS, getDownloadListings } from '../../../lib/download-manifest'
-import type { DirListing } from '../../../../types/download'
+import type { DirListing } from '@lib/download/types'
 
 const allListings = getDownloadListings()
 

dashboard/src/components/download/DownloadListingContent.tsx

@@ -8,7 +8,7 @@ import { useLanguage } from '@i18n/LanguageProvider'
 import { translations } from '@i18n/translations'
 import { formatDate } from '@lib/format'
 import { formatSegmentLabel, type DownloadSection } from '@lib/download-data'
-import type { DirListing } from '../../types/download'
+import type { DirListing } from '@lib/download/types'
 
 type DownloadListingContentProps = {
   segments: string[]

dashboard/src/components/download/FileTable.tsx

@@ -6,7 +6,7 @@ import CopyButton from './CopyButton'
 import { useLanguage } from '@i18n/LanguageProvider'
 import { translations } from '@i18n/translations'
 import { formatBytes, formatDate } from '../../lib/format'
-import type { DirListing } from '../../types/download'
+import type { DirListing } from '@lib/download/types'
 
 interface FileTableProps {
   listing: DirListing

dashboard/src/lib/download-data.ts

@@ -1,4 +1,4 @@
-import type { DirListing } from '../types/download'
+import type { DirListing } from '@lib/download/types'
 
 export interface DownloadSection {
   key: string

dashboard/src/lib/download-manifest.ts

@@ -3,7 +3,7 @@ import 'server-only'
 import fs from 'node:fs'
 import path from 'node:path'
 
-import type { DirListing } from '../types/download'
+import type { DirListing } from '@lib/download/types'
 
 const readListings = (relativePath: string): DirListing[] => {
   try {