fix(skilldoc): regenerate incident/alert cards for --fields flag

The --fields projection flag added to `incident list` / `alert list`
changed the cobra command tree, leaving the generated card fences stale.
CI 'Check skill command-cards' (go run ./internal/cmd/skilldoc check)
failed on reference/{alert,incident}.md. Regenerated via make gen-cards.

Author: ysyneu

skills/flashduty/reference/alert.md

@@ -74,6 +74,7 @@ Get alert detail
 List alerts
 - `--active` bool
 - `--channel` string
+- `--fields` string
 - `--limit` int
 - `--muted` bool
 - `--page` int

skills/flashduty/reference/incident.md

@@ -185,6 +185,7 @@ Get incident detail
 ### list
 List incidents
 - `--channel-id` int64
+- `--fields` string
 - `--limit` int
 - `--nums` string
 - `--page` int