Fix: the server crashed on every Search; Search now covers tasks and events and explains itself

- Restore ddgAnswer, which an earlier edit deleted: /api/ddg threw a ReferenceError and killed the
  whole server process whenever Search ran
- One failing request can no longer take the server down (errors are logged and answered with a 500)
- tools/smoke-test.js starts the real server and calls every endpoint; the Gitea workflow runs it before
  building the image, so a missing function or a crash stops the build
- Search: also searches NE Hub tasks and calendar events; Seafile file search falls back to scanning file
  names when the search index returns nothing; Plex search falls back to the library's artists/albums;
  a status line shows what was searched, per-source counts and errors, with sign-in links

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Dockerfile

@@ -2,7 +2,7 @@ FROM node:22-alpine
 WORKDIR /app
 COPY package.json package-lock.json ./
 RUN npm ci --omit=dev
-COPY server.js auth.js cal.js ics.js caldav.js tasks.js settings.js ./
+COPY server.js auth.js cal.js ics.js caldav.js tasks.js settings.js search.js ./
 COPY public ./public
 ENV PORT=8080 DATA_DIR=/data
 RUN mkdir -p /data && chown node:node /data