chore: remove duplicate copies of the site, download center and installers (WS-C)

The landing page, download pages, invite page, assetlinks and installers
existed in two or three places; only site/ and the Forgejo feed are served.

- apps/api-server/wwwroot: delete the stale site build, download/invite
  pages, .well-known copy, legacy static admin and 1.0.0 binaries. The API
  no longer serves static files (UseStaticFiles/fallbacks and the apk/zip
  blocker removed); the Next admin is the only admin UI.
- Delete 19 tracked installers/packages (~568 MiB) under site/public/releases,
  apps/web/public/releases and wwwroot/releases; .gitignore blocks them.
- apps/web: delete the download/releases pages, desktop-release.ts, the
  download.html and assetlinks copies, and the accept-invite page (invites
  are only issued to the site's /accept-invite/). e2e specs call the /app
  base path and check the /download redirect instead.
- scripts: delete the retired release/NAS site scripts, drop the web target
  from sync-version, and check assetlinks in site/public only.
- Delete the unused Dockerfile.admin (apps/admin/Dockerfile is used).

Policy: docs/REFACTOR_POLICY.md Wave 3, W3-5 and W3-6.

apps/web/e2e/smoke.spec.ts

@@ -10,36 +10,31 @@ import { test, expect } from '@playwright/test'
 
 test.describe('Smoke: unauthenticated access', () => {
   test('루트(/)는 /login으로 리다이렉트된다 (Supabase 미설정 시)', async ({ page }) => {
-    await page.goto('/')
+    await page.goto('/app')
     await page.waitForURL(/\/login/, { timeout: 10000 })
     expect(page.url()).toContain('/login')
   })
 
   test('/login 페이지가 로드되고 D3RO VOICE 로고가 표시된다', async ({ page }) => {
-    await page.goto('/login')
+    await page.goto('/app/login')
     await expect(page.getByText(/D3RO[- ]VOICE/i)).toBeVisible({ timeout: 10000 })
   })
 
   test('/login에 Google/GitHub OAuth 버튼이 보인다', async ({ page }) => {
-    await page.goto('/login')
+    await page.goto('/app/login')
     await expect(page.getByRole('button', { name: /Google/i })).toBeVisible()
     await expect(page.getByRole('button', { name: /GitHub/i })).toBeVisible()
   })
 
   test('/dashboard는 미로그인 시 /login으로 리다이렉트', async ({ page }) => {
-    await page.goto('/dashboard')
+    await page.goto('/app/dashboard')
     await page.waitForURL(/\/login/, { timeout: 10000 })
     expect(page.url()).toContain('/login')
   })
 
   test('/meetings도 미로그인 시 /login으로 리다이렉트', async ({ page }) => {
-    await page.goto('/meetings')
+    await page.goto('/app/meetings')
     await page.waitForURL(/\/login/, { timeout: 10000 })
     expect(page.url()).toContain('/login')
   })
-
-  test('/accept-invite?token=bogus는 페이지 로드 (에러 메시지 표시)', async ({ page }) => {
-    await page.goto('/accept-invite?token=bogus')
-    await expect(page.getByText(/TEAM INVITE/i)).toBeVisible({ timeout: 10000 })
-  })
 })