Fix docs capture default account role

Found during the docs-writer run (Task 8198). apps/docs/WRITER.md treats the capture helper's default sign-in as the TimeSaver org's *member* and `--as admin` as its Org Owner, so member screenshots show what a member sees and org-admin-only controls are shot separately. On prod the default account is not a plain member: it opens `/automations` and `/org/billing` (both `org_admin`-guarded; `PROBE … ok`), and Support shows the **Org** tab, which `offeredScopes` (apps/web/src/lib/support.ts) offers only to an Org Owner/Admin seat. Requirements: 1. Confirm which org role the default capture account holds on prod; if it is Owner/Admin, give the TimeSaver org a real member account for the default (through the console), or correct WRITER.md's description of the two accounts. 2. Make the capture helper refuse (or warn) when its default account opens an `org_admin`-guarded route, so a mis-provisioned member is caught on the next run instead of silently photographing admin-only controls as member screens. Out of scope: re-shooting existing pages (the docs-writer schedule refreshes them), any change to role resolution in the API. Done means: - `node apps/docs/capture/capture.mjs --probe /automations` as the default account answers `no-access` (or the helper flags it), and `--as admin` answers `ok`. - WRITER.md's account description matches what each account holds.

The default capture account held Org Admin via the timesaver-admins group on prod. Removed it in the console; it is now a plain member. capture.mjs refuses an identity whose org role is wrong. Probes: member no-access, admin ok. WRITER.md fixed. Quick gate green. PR #6356 queued. Follow-up #8218. Memory: proposed 1 qa.