chore: lint via biome, current Open Plugins links, cron-auth constant-time compare, CI token scope, single biome version

[deanrie]

Summary

Repo housekeeping, no behaviour change for valid requests. Consolidated from #445 and #446 (both closed in favour of this PR; commits carried unchanged, one each).

1. chore: point docs at agent-plugins.org, make lint run biome, document detected manifests and commands (was chore: fix lint script for Next 16, update Open Plugins links, document detected manifests and commands #445). apps/cursor/package.json still had "lint": "next lint", which Next.js 16 removed, so bun run lint failed while AGENTS.md listed it as a standard command; it now runs biome check ., same as CI. open-plugins.com 308-redirects to agent-plugins.org (and /plugin-builders/specification to /specification); README, the submission form, /plugins/new and the parser's error message now use the current host, nuqs.47ng.com likewise moved to nuqs.dev. The README auto-detect table now lists what the parser actually accepts (mcp.json as well as .mcp.json, commands/*.md, manifests under .plugin/, .cursor-plugin/, .claude-plugin/, monorepo sub-plugins from .cursor-plugin/marketplace.json).
2. chore: constant-time cron secret compare, least-privilege CI token, single biome version (was chore: constant-time cron secret compare, least-privilege CI token, single biome version #446). cron-auth.ts compared the cron secret with !==; it now uses crypto.timingSafeEqual on equal-length buffers (length checked first, missing header reads as "" and still 401s). ci.yml gains permissions: contents: read and a concurrency group. Biome was ^2.4.15 at the root and 2.4.14 in apps/cursor; both now 2.4.15, bun.lock loses the duplicate entry and keeps configVersion.

Verification

• bun install --frozen-lockfile: clean, bun.lock still carries "configVersion": 0.
• bunx biome ci . in apps/cursor: 184 files, no fixes, 5 pre-existing warnings.

[vercel]

@deanrie is attempting to deploy a commit to the Anysphere Team on Vercel.

A member of the Team first needs to authorize it.