The tasks manual sends people to Spending for the tasks-at-once setting #1454

Found on santos/dev2 at 008363c98 (#1410). It reaches dev when #1410 merges.

What happened

The manual locates task.parallel in category spending. /settings shows it under Tasks as tasks at once, so someone following the page searches the wrong section.

Replication

Deterministic (no model). Run codeaf manual "where is task.parallel", then open /settings in codeaf chat. The answer says spending; the visible row is under Tasks and reads tasks at once.

Where

internal/manual/chat/tasks.md:4219 gives the wrong category at 008363c98. internal/config/settings.go:2347 defines the visible label and category.

The fix

Replace the category with Tasks and name the row exactly as drawn.

Acceptance

• e2e: the manual command says Tasks and tasks at once, matching /settings.
• Unit: a manual probe for the setting reaches the corrected section.
• The change entry's invalidates notes the former category.