feat(FN-847): add conditional Workflow tab to TaskDetailModal

- Show Workflow tab for tasks with enabled workflow steps OR previous workflow results
- Add comprehensive tests for TaskDetailModal workflow tab visibility
- Add workflow tab styles including step result cards and status badges
- Clean up TerminalModal and useTerminalSessions (remove unused code and tests)
- Remove dashboard README section on terminal sessions

packages/dashboard/app/styles.css

@@ -16740,6 +16740,113 @@ html .column.drag-over * {
   }
 }
 
+/* ── Workflow Results ── */
+.workflow-results-loading {
+  display: flex;
+  align-items: center;
+  gap: var(--space-sm, 8px);
+  padding: var(--space-md, 16px);
+  color: var(--text-muted, #8b949e);
+  font-size: 14px;
+}
+
+.workflow-results-spinner {
+  width: 16px;
+  height: 16px;
+  border: 2px solid var(--border, #30363d);
+  border-top-color: var(--todo, #58a6ff);
+  border-radius: 50%;
+  animation: spin 0.6s linear infinite;
+}
+
+@keyframes spin {
+  to { transform: rotate(360deg); }
+}
+
+.workflow-results-empty {
+  padding: var(--space-md, 16px);
+  text-align: center;
+  color: var(--text-muted, #8b949e);
+}
+
+.workflow-results-empty-hint {
+  font-size: 12px;
+  margin-top: var(--space-xs, 4px);
+  opacity: 0.7;
+}
+
+.workflow-results-list {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-md, 16px);
+}
+
+.workflow-result-item {
+  border: 1px solid var(--border, #30363d);
+  border-radius: 8px;
+  padding: var(--space-md, 16px);
+  background: var(--surface-elevated, #161b22);
+}
+
+.workflow-result-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: var(--space-sm, 8px);
+  margin-bottom: var(--space-xs, 4px);
+}
+
+.workflow-result-name {
+  font-weight: 600;
+  font-size: 14px;
+  color: var(--text-primary, #e6edf3);
+}
+
+.workflow-result-badge {
+  display: inline-block;
+  padding: 2px 8px;
+  border-radius: 12px;
+  font-size: 11px;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+}
+
+.workflow-result-meta {
+  display: flex;
+  gap: var(--space-sm, 8px);
+  font-size: 12px;
+  color: var(--text-muted, #8b949e);
+  margin-bottom: var(--space-xs, 4px);
+}
+
+.workflow-result-output-section {
+  margin-top: var(--space-sm, 8px);
+}
+
+.workflow-result-output-label {
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--text-muted, #8b949e);
+  margin-bottom: var(--space-xs, 4px);
+}
+
+.workflow-result-output {
+  background: var(--surface-dimmed, #0d1117);
+  border: 1px solid var(--border, #30363d);
+  border-radius: 6px;
+  padding: var(--space-sm, 8px) var(--space-md, 16px);
+  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
+  font-size: 12px;
+  line-height: 1.5;
+  color: var(--text-primary, #e6edf3);
+  white-space: pre-wrap;
+  word-break: break-word;
+  overflow-x: auto;
+  max-height: 300px;
+  overflow-y: auto;
+}
+
 /* ── Light Theme ── */
 [data-theme="light"] .mission-manager {
   background: var(--surface);