fix: fall back to summary when title is empty in formatCell (#380)

The reports/upcoming API uses the calendar partial
(schedules/calendar/_entry.json.jbuilder) which emits summary but
not title for schedule entries. The SDK deserializes the missing
field to an empty string, so formatCell's existing name → title → id
chain was appending "" for each entry and joining them into
", , , , ..." in --md and styled output.

Add summary as a fallback between title and id, and add empty-string
guards on the name and title checks so an empty field doesn't
silently win over a non-empty one lower in the chain.

Schedule::Entry#title delegates to summary in bc3, so the two fields
carry identical data when both are present; summary is the canonical
field in the calendar API response.

Fixes: reports schedule --md showing blank entry names

Author: robzolkos

internal/output/output_test.go

@@ -870,6 +870,30 @@ func TestFormatCellWithMapArray(t *testing.T) {
 	}
 	result = formatCell(attachments)
 	assert.Equal(t, "100, 200", result)
+
+	// Test maps with summary fallback (schedule entries: the reports/upcoming API
+	// uses the calendar partial which emits summary but not title, so title arrives
+	// as an empty string from the SDK zero-value; summary must win).
+	entries := []any{
+		map[string]any{"id": float64(1), "title": "", "summary": "Team standup"},
+		map[string]any{"id": float64(2), "title": "", "summary": "Paul G OUT (Sabbatical)"},
+	}
+	result = formatCell(entries)
+	assert.Equal(t, "Team standup, Paul G OUT (Sabbatical)", result)
+
+	// Test that a non-empty title still wins over summary.
+	withBoth := []any{
+		map[string]any{"id": float64(1), "title": "Explicit title", "summary": "Summary text"},
+	}
+	result = formatCell(withBoth)
+	assert.Equal(t, "Explicit title", result)
+
+	// Test that an empty name does not shadow a valid title (empty-string guard).
+	emptyName := []any{
+		map[string]any{"id": float64(1), "name": "", "title": "A task"},
+	}
+	result = formatCell(emptyName)
+	assert.Equal(t, "A task", result)
 }
 
 // =============================================================================

internal/output/render.go

@@ -763,11 +763,16 @@ func formatCell(val any) string {
 			case int, int64:
 				items = append(items, fmt.Sprintf("%d", elem))
 			case map[string]any:
-				// Try name, then title, then id, then fallback
-				if name, ok := elem["name"].(string); ok {
+				// Try name → title → summary → id.
+				// summary is checked after title because schedule entries omit title
+				// from the calendar/reports API response and use summary as their
+				// display name (Schedule::Entry#title delegates to summary in bc3).
+				if name, ok := elem["name"].(string); ok && name != "" {
 					items = append(items, ansi.Strip(name))
-				} else if title, ok := elem["title"].(string); ok {
+				} else if title, ok := elem["title"].(string); ok && title != "" {
 					items = append(items, ansi.Strip(title))
+				} else if summary, ok := elem["summary"].(string); ok && summary != "" {
+					items = append(items, ansi.Strip(summary))
 				} else if id, ok := elem["id"]; ok {
 					items = append(items, fmt.Sprintf("%v", id))
 				}