Expose queue paused-status via shigoto_dashboard

[Taure]

Problem

Queue paused-state lives in the shigoto_queue gen_server (#state.paused) and isn't queryable through the public dashboard API. shigoto_dashboard:queue_stats/0 returns per-queue counts but no paused flag, and there's no shigoto:paused_queues/0 (only pause_queue/1 / resume_queue/1).

Impact

A polling dashboard can't show authoritative pause state. In shigoto_board (Taure/shigoto_board#7) the queues Status badge always renders "active" even when a queue is paused; pause/resume still work, but the displayed status can't reflect reality without this query.

Proposal

Expose paused-status through the dashboard surface, e.g. either:

• include is_paused => boolean() in each queue_stats/0 row (preferred — one round-trip, no extra call), or
• add shigoto_dashboard:paused_queues/0 -> {ok, [binary()]}.

Reading it likely means asking each live shigoto_queue for its paused field (or tracking it where pause/resume already write).

Consumer

shigoto_board already plumbs an is_paused flag per queue row (defaults to false); it will light up the badge automatically once queue_stats/0 provides it.