cards: a document and its cards, seen from both ends

A document now lists the cards about it: the ones whose notes it is and
the ones whose description links to it. GET /nodes/{id}/cards answers
that, and the node itself carries it as `cards`. A line under the
document's meta line says what is still open and when it is first due;
it and `gc` open a new cards part of the info sheet, where j/k picks a
card, Space, H/L, D, a and `:` act on it, and Enter turns it over on its
board. `c` while reading a document makes a card about it.

Card verbs act on the card in focus wherever it is looked at: the
board's cursor, the card turned over, the agenda's highlight, the card
picked in the info sheet, or a document's only open card. patchCard,
sendCard and toggleDone take that card, so patchAgendaCard,
sendAgendaCard and finishCard are gone, and :due, :repeat, :label and
:done no longer refuse to run away from the board.

Migration 0027 adds card_links, links for a card's description: indexed
on every write, backfilled on start, followed and rewritten on a rename
or move like a document's, and claimed when a title they named appears.
It also adds cards_fts over title, description and checklist steps;
GET /cards?q= searches it, and / lists the cards found after the nodes,
Enter turning one over on its board.

web/src/lib/api.ts

@@ -53,6 +53,8 @@ export interface WorkspaceNode extends NodeSummary {
   path: Crumb[]
   /** How many documents link here. */
   backlinks: number
+  /** The cards about it — its own, and those whose summary links here — open ones first. */
+  cards: AgendaCard[]
   /** Where each `[[title]]` in the body leads, as an /n/ path; a title that leads nowhere is missing. */
   wikilinks: Record<string, string>
 }
@@ -191,12 +193,16 @@ export interface Moved extends Card {
   again: Card | null
 }
 
-/** An open card as the agenda lists it, with the board it lives on. */
+/**
+ * A card with the board it lives on: as the agenda lists it, as a document
+ * lists the cards about it, and as a search finds it.
+ */
 export interface AgendaCard extends Card {
   space_id: number
   space_slug: string
   list_name: string
-  role: 'inbox' | 'doing'
+  /** The agenda only ever has the first two. */
+  role: 'inbox' | 'doing' | 'done'
 }
 
 export interface Agenda {
@@ -456,6 +462,11 @@ export const api = {
   },
 
   getNode: (id: number) => request<WorkspaceNode>(`/nodes/${id}`),
+  /** The cards about a document, as `getNode` has them. */
+  nodeCards: (id: number) => request<AgendaCard[]>(`/nodes/${id}/cards`),
+  /** The cards whose title, summary or steps match — in one space's board with `space`. */
+  searchCards: (q: string, space?: number) =>
+    request<AgendaCard[]>(`/cards?${new URLSearchParams(space === undefined ? { q } : { q, space: String(space) })}`),
 
   /** `work/einarbeiten/01-was-ist-eebus` — the node behind a `/n/...` address. */
   resolvePath: (path: string) => request<WorkspaceNode>(`/resolve?path=${encodeURIComponent(path)}`),