Rewrite Workflow settings UI to match the group+flowchart demo #1364

Owner: Dev4 — Workflow settings UI rewrite, queued after #1367 (Lead, 2026-10-27).

Ask

Owner 2026-10-27: the Settings → 工作流 page is wrong / messy — rewrite it completely.

What is wrong (screenshot attached)

Current settings pane shows a bare text dump: 「工作流就是一个文件：workflows/<id>.json…」 with sections 出厂预设 / 你自己的 stuck on 「正在读取工作流…」. That is not the product surface.

Target

Match the HTML demo (flybot-workflow-demo: group-shaped Workflow chat + drag-drop flowchart canvas + task assign), already scoped in #1318 / merged #1330. Settings → 工作流 should list/manage workflows in FlyBot UI language (not a JSON-file tutorial), open the visual graph editor, and support predefined + Bot-defined workflows.

Done when

1. Settings → 工作流 no longer shows the file-path tutorial / stuck loading copy as the main UI.
2. User can see factory + own workflows and open the graph editor (drag-drop) from that entry.
3. PR with Fixes #; keep task/kanban; do not revive the delivery board (Remove the delivery board (GitHub repo metrics panel) #1363 removes it).