Closes#520.
The login action stores `Basic <base64>` in an HttpOnly `auth_token`
cookie. SSR fetches from hooks.server.ts explicitly set the
Authorization header. Vite's dev proxy does the same on every
/api/* request. Caddy in production does NOT. So browser-side
fetch() and EventSource() calls reach the backend without auth,
get 401 + WWW-Authenticate: Basic, and the browser pops a native
auth dialog over the SPA.
Add AuthTokenCookieFilter (Ordered.HIGHEST_PRECEDENCE, before any
Spring Security filter) that promotes the cookie to a request
header when no explicit Authorization is present. URL-decodes the
cookie value because SvelteKit URL-encodes spaces ("Basic " ->
"Basic%20") when serializing the cookie. Works the same for REST,
SSE (/api/notifications/stream, /api/ocr/jobs/.../progress), and
any other browser-direct backend call.
5 tests in AuthTokenCookieFilterTest cover: URL-decoded promotion,
explicit-Authorization-wins precedence, no-cookies pass-through,
absent-auth-token pass-through, empty-value pass-through.
Also: add `@ActiveProfiles("test")` to ThumbnailServiceIntegrationTest,
the one remaining @SpringBootTest in the suite that wasn't annotated.
After #516 made UserDataInitializer fail-closed outside dev/test/e2e,
this test's context load was throwing. Restores green main.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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