Add TUI kanban board, review workflow, and new task statuses

Replace task statuses (pending/running/succeeded/failed/cancelled) with
a kanban workflow: todo → in_progress → in_review → done/wontdo.

When a non-review agent task completes, the API auto-creates a child
review task and moves the parent to in_review. Only humans can move
tasks from in_review to done/wontdo via the TUI.

New components:
- cmd/tui: bubbletea kanban board with $EDITOR integration
- POST /api/v1/tasks/{id}/complete: agent completion callback
- Operator --api-url flag for completion callbacks
- ProviderQueue sets tasks to in_progress on pickup
- AgentTask reconciler calls /complete on job finish

internal/tui/card.go

@@ -0,0 +1,91 @@
+package tui
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/charmbracelet/lipgloss"
+
+	"git.unkin.net/unkin/forgebot/pkg/models"
+)
+
+func renderCard(task models.Task, width int, selected bool) string {
+	color := statusColors[task.Status]
+
+	style := cardStyle.Width(width - 4)
+	if selected {
+		style = cardSelectedStyle.Width(width - 4).BorderForeground(color)
+	}
+
+	cmd := lipgloss.NewStyle().Bold(true).Render(task.Command)
+
+	repo := task.Repository
+	maxRepo := width - 6
+	if maxRepo > 0 && len(repo) > maxRepo {
+		repo = repo[:maxRepo-1] + "…"
+	}
+	repo = dimStyle.Render(repo)
+
+	var ref string
+	if task.IssueNumber > 0 {
+		ref = fmt.Sprintf("#%d", task.IssueNumber)
+	} else if task.PRNumber > 0 {
+		ref = fmt.Sprintf("PR#%d", task.PRNumber)
+	}
+	if task.Ref != "" {
+		if ref != "" {
+			ref += " " + task.Ref
+		} else {
+			ref = task.Ref
+		}
+	}
+	ref = dimStyle.Render(ref)
+
+	elapsed := relativeTime(task.CreatedAt)
+	if task.Status == models.StatusInProgress && task.StartedAt != nil {
+		elapsed = relativeTime(*task.StartedAt)
+	}
+	if (task.Status == models.StatusDone || task.Status == models.StatusWontdo) && task.CompletedAt != nil {
+		elapsed = relativeTime(*task.CompletedAt)
+	}
+
+	bottomLine := elapsed
+	if task.Author != "" {
+		pad := width - 6 - len(elapsed) - len(task.Author)
+		if pad < 1 {
+			pad = 1
+		}
+		bottomLine = elapsed + strings.Repeat(" ", pad) + task.Author
+	}
+	bottomLine = dimStyle.Render(bottomLine)
+
+	content := lipgloss.JoinVertical(lipgloss.Left, cmd, repo, ref, bottomLine)
+
+	if task.Status == models.StatusWontdo {
+		content = dimStyle.Render(content)
+	}
+	if task.ErrorMessage != "" && task.Status == models.StatusTodo {
+		errHint := task.ErrorMessage
+		if len(errHint) > width-6 {
+			errHint = errHint[:width-7] + "…"
+		}
+		content += "\n" + errStyle.Render(errHint)
+	}
+
+	return style.Render(content)
+}
+
+func relativeTime(t time.Time) string {
+	d := time.Since(t)
+	switch {
+	case d < time.Minute:
+		return "just now"
+	case d < time.Hour:
+		return fmt.Sprintf("%dm ago", int(d.Minutes()))
+	case d < 24*time.Hour:
+		return fmt.Sprintf("%dh ago", int(d.Hours()))
+	default:
+		return fmt.Sprintf("%dd ago", int(d.Hours()/24))
+	}
+}