fix(adapters): handle recent extraction drift

[jackwener]

Summary\n\nThis is the low-risk adapter-local batch from the latest issue sweep. It keeps the fixes inside the affected adapters/shared adapter helpers and avoids bridge/runtime lifecycle changes.\n\nFixes #2287\nFixes #2273\nFixes #2263\nFixes #2235\nFixes #2214\nAddresses #2205\n\n## Changes\n\n- discord-app read: when the normal message content node is empty, fall back to visible embed text so embed-only messages are not dropped.\n- twitter profile: resolve full UserByScreenName operation metadata, not only the query id, and send current features/fieldToggles with the GraphQL request.\n- linkedin people-search: collapse exact duplicated leading profile-name halves before matching names against main.innerText boundaries.\n- douban whoami: verify identity through the /mine redirect/profile links, with dbcl2 uid fallback, instead of treating account-settings nav hrefs as auth failure.\n- notebooklm: accept the observed Google redirect host notebook.google.com while preserving explicit NotebookLM host validation.\n- douyin browserFetch: detect empty 200/non-JSON bodies before JSON.parse so hashtag search no longer reports JSON.parse("") / Unexpected end as the root failure. This is intentionally scoped to error classification; if the endpoint still returns no data, command success needs separate endpoint evidence.\n\n## Verification\n\n- npx vitest run clis/douban/auth.test.js clis/discord-app/.test.js clis/twitter/profile.test.js clis/linkedin/people-search.test.js clis/notebooklm/.test.js clis/douyin/_shared/browser-fetch.test.js clis/douyin/hashtag.test.js --reporter=dot\n- npm run typecheck\n- git diff --check\n- npx tsx src/main.ts validate douban\n- npx tsx src/main.ts validate discord-app\n- npx tsx src/main.ts validate twitter/profile\n- npx tsx src/main.ts validate linkedin/people-search\n- npx tsx src/main.ts validate notebooklm\n- npx tsx src/main.ts validate douyin\n- npm run build\n\n## Issue sweep notes\n\nClosed as already fixed on current main before this PR:\n\n- #2284: OPENCLI_WINDOW / --window is now documented in README.md, README.zh-CN.md, src/help.ts, src/commanderAdapter.ts, and browser help examples.\n- #2234: Instagram business/professional account web_profile_info fallback is already covered by current profile/shared-user-id/feed-by-username code and tests.\n\nDeferred as not low-risk for this batch:\n\n- #2283 JD reviews needs authenticated/current JD comment API behavior, not just a DOM parser patch.\n- #2217 Nowcoder mixed content/moment identity is a schema/contract redesign.\n- #2197 Douyin stats needs endpoint discovery for the retired metrics_trend endpoint.\n