One board, step 2: drop the tablist, draw columns from the workflow, filters for review / done-today #1326

Part of #1265 — step 2 of 4 (steps 1 and 4 already shipped as #1277/#1276 and #1293/#1297).

Written-by: FlyBot
Owner: Dev4

Owner constraint (2026-10-27)

Do not build or expand a code-dev "view this repo's PR counts / delivery metrics" surface. Leave the existing multi-repo read path (#1297) alone; this step is board UI only.

What this step is

Unify the dialog into one board and make columns definition-driven, per Chief's HTML spec on #1265 (6413937162) and the #1272 correction that columns come from the card's workflow (column: false stages become filters).

Anchors on main today (read 2026-10-27):

• Tablist still in core/src/client/kanban.js (~408–411): Tasks / Delivery buttons; heading switches by view; DeliveryView mounted when view === 'delivery'.
• Host columns still DELIVERY_COLUMNS = ['raw','ready','working','review','done-today'] in core/src/host/delivery-board.js:17; columnOfDelivery still maps labels to those five.
• Client stagesOf / DELIVERY_COLUMNS in core/src/client/delivery-view.js:35+ still default to the five; feat(workflow): the Workflows page, and columns drawn from the definition (#1272 step 3) #1304 already draws workflow sections for cards that name workflow: / node:, but the tab split and five legacy lanes remain.
• Shared lanes: core/src/shared/task-board.js and core/src/shared/workflow-board.js (columnPlan / workflowColumns).

Required shape (markup)

1. Frame. Keep div.bt-mem.bt-board[role=dialog]. Delete div.bt-board-views[role=tablist] and both button[data-view]. h2#bt-board-heading text becomes Board. Body is one view: div.bt-del-body[data-view=board] (or equivalent single body) that draws both GitHub cards and task cards — no second tab.
2. Columns. Visible columns come from the workflow definition in play (workflowColumns / columnPlan), not a hard-coded triple or five. Stages marked column: false (e.g. review, and done-today as a filter) are not lanes. Cards carry data-stage for the delivery stage attribute so existing stage assertions can keep working without a fifth column.
3. Filters. div.bt-del-filters with button.bt-soft.bt-soft-sm[data-filter=all|review|done-today] and aria-pressed. A filter narrows the columns; it never reorders them.
4. Cards. Reuse the shared BoardCard from step 1 (data-source / data-key). Task-only cards (no repository) sit in the same columns with no repo badge. Do not implement hanging a FlyBot record under an issue card here — that is step 3.
5. Degradation. With no GitHub token / failed snapshot, task cards still render and the board says the GitHub side is unavailable — never an empty board (Delivery view fails whole when one request fails: a 404 reads as no GitHub connection, with no retry and no per-endpoint diagnosis #1211).
6. i18n + generated. New strings in core/src/client/i18n.js; rebuild core/client.js and regenerate patches/ds-bot/ (build-client --check, ds-bot-patches generate + check).

Out of scope

• Multi-repository (done).
• Linking FlyBot records under issue cards (step 3).
• Any new delivery header metrics, open-PR tallies, or "how many PRs in this repo" UI.
• Closing issues from the board; writing issue state back to GitHub.

Done when

• No tablist; dialog opens on one board titled Board.
• Columns are the visible stages of the workflow(s) in play; review / done-today are filters.
• Task cards and GitHub cards share that board; with no token, tasks still show.
• Tests updated in the same PR: core/test/kanban.test.js (tab assertions removed), core/test/delivery-view.test.js, core/test/delivery-board.test.js as needed; red-without-change knives documented.
• PR body: Fixes #<this issue> and Part of #1265 (do not Fixes #1265 yet).

Red without the change

1. Asserting role=tablist / data-view=tasks|delivery still finds the old tabs → this PR's kanban test goes red when the tablist is gone, and stays green only with the new single-board assertions.
2. Asserting five section[data-column] for raw|ready|working|review|done-today on a repo-dev board → red once columns come from the definition's visible stages.
3. With a failed / no-token delivery snapshot, the board still shows at least one task card fixture and copy that names the GitHub side unavailable — emptying the body for a failed delivery read makes that test red.