feat(kanban): full read/write board with per-project tenants

Lifts Scarf's Kanban surface from the v2.6 read-only list to a
drag-and-drop board with the complete Hermes v0.12 mutation surface
wired up, plus per-project boards bound to a Scarf-minted tenant slug
and a read-only board on iOS.

Why now: the v2.6 list was a placeholder shipped while upstream Kanban
collab was still mid-rework. v0.12 stabilized the 27-verb CLI; this
release makes Scarf a real GUI client for it. Driving real tasks
end-to-end exposed and closed a connected bug pattern (claim vs
dispatch, silent skipped_unassigned, integer-vs-ISO timestamps,
parser-leaked "(no" sentinel) that would have shipped as latent UX
papercuts otherwise.

ScarfCore: KanbanService actor (Sendable, pure I/O) wrapping every
verb; KanbanTenantReader cross-platform manifest projection; eight
new model types (TaskDetail, Comment, Event, Run, Stats, Assignee,
CreateRequest, Filters); KanbanError; pure transition planner that
maps drag-drop column changes to verb sequences, tested against
canonical Hermes JSON fixtures.

Mac: KanbanBoardView orchestrator with five-column drag-drop layout,
optimistic-merge state, KanbanInspectorPane side-pane (Comments /
Events / Runs / Log tabs, Log streams worker stdout every 2s while
running), inline assignee picker, health banner for unassigned and
last-failed-run states. New Task sheet defaults to active profile
and auto-fires kanban dispatch on submit. Sidebar moved Kanban from
Manage to Monitor. Read-only KanbanListView preserved as Board|List
toggle for narrow windows / accessibility.

Per-project: DashboardTab.kanban tab on every project gated on
hasKanban; KanbanTenantResolver mints scarf:<slug> tenants on first
interaction and persists to .scarf/manifest.json (immutable across
rename); ProjectAgentContextService surfaces the tenant in the
AGENTS.md scarf-managed block so agents pass --tenant <slug> on
kanban create. New kanban_summary dashboard widget; vocabulary
mirrored in tools/widget-schema.json and site/widgets.js.

iOS: read-only board on the project tab via paged single-column
Picker, modal detail sheet with Comments / Events / Runs. Mutations
+ drag-drop deferred to v2.8.

Tests: 19 new pure-logic tests covering decoding, planner verb
mapping, argv assembly, glance string formatting, and parser
rejection of the kanban assignees empty-state sentinel. All 348
ScarfCore tests pass.

Constraints documented in CLAUDE.md: no within-column reorder
(Hermes has no update --priority verb); no live watch streaming
yet (5s polling for board, 2s for log); no bulk re-tag for legacy
NULL-tenant tasks. Pre-v0.12 Hermes hosts gracefully hide the
surface end-to-end.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

site/widgets.js

@@ -81,6 +81,7 @@
         case "markdown_file": return renderMarkdownFile(widget);
         case "image":       return renderImage(widget);
         case "status_grid": return renderStatusGrid(widget);
+        case "kanban_summary": return renderKanbanSummary(widget);
         default:         return renderUnknown(widget);
       }
     } catch (e) {
@@ -536,6 +537,27 @@
     return card;
   }
 
+  // ---------------------------------------------------------------------
+  // Kanban summary (catalog preview — no live kanban data)
+  // ---------------------------------------------------------------------
+
+  function renderKanbanSummary(widget) {
+    const card = elt("div", "widget widget-kanban-summary");
+    const head = elt("div", "widget-cron-head");
+    const icon = elt("span", "widget-cron-icon", "▤");
+    head.appendChild(icon);
+    head.appendChild(elt("span", "widget-title", widget.title || "Kanban"));
+    card.appendChild(head);
+    card.appendChild(elt("div", "widget-cron-meta",
+      "Live Kanban summary appears in Scarf after install."));
+    const maxRows = (widget.value && typeof widget.value === "number")
+      ? Math.max(1, Math.floor(widget.value))
+      : 3;
+    card.appendChild(elt("div", "widget-cron-hint",
+      `Shows up to ${maxRows} top in-progress / blocked / todo tasks for the project's Kanban tenant.`));
+    return card;
+  }
+
   // ---------------------------------------------------------------------
   // Cron status (catalog preview — no live cron data)
   // ---------------------------------------------------------------------