Remove buttons: confirm + block program removal with active deployments

The Stage 2 editor split dropped the old confirm() — Remove program/service/job
deleted immediately on click. Restored confirmation on all three (FormFooter
window.confirm with a per-type message).

Removing a program that still has services/jobs referencing it would orphan
their program: ref. Now blocked:
- API: DELETE /config/programs/{name} → 409 'Programs with active jobs or
  services cannot be removed. Delete these first: …' (authoritative).
- App: ProgramFields shows the blocked reason instead of a Remove button when
  the program has deployments.
- CLI: castle delete refuses a program with referencing deployments not named
  the same (which would survive the delete dangling).

Verified live: DELETE program lakehouse → 409. api 52 / cli 24 green; build clean.

app/src/components/detail/JobFields.tsx

@@ -74,6 +74,7 @@ export function JobFields({ job, onSave, onDelete }: Props) {
         onSave={handleSave}
         onDelete={onDelete ? () => onDelete(job.id) : undefined}
         deleteLabel="Remove job"
+        confirmMessage={`Remove job "${job.id}" from castle.yaml? Run a deploy afterward to tear down its timer.`}
       />
     </div>
   )

app/src/components/detail/ProgramFields.tsx

@@ -95,6 +95,12 @@ export function ProgramFields({ program, onSave, onDelete }: Props) {
         onSave={handleSave}
         onDelete={onDelete ? () => onDelete(program.id) : undefined}
         deleteLabel="Remove program"
+        confirmMessage={`Remove program "${program.id}" from castle.yaml? (Source on disk is untouched.)`}
+        deleteBlocked={
+          program.services.length + program.jobs.length > 0
+            ? "Programs with active jobs or services cannot be removed — delete those first."
+            : undefined
+        }
       />
     </div>
   )

app/src/components/detail/ServiceFields.tsx

@@ -119,6 +119,7 @@ export function ServiceFields({ service, onSave, onDelete }: Props) {
         onSave={handleSave}
         onDelete={onDelete ? () => onDelete(service.id) : undefined}
         deleteLabel="Remove service"
+        confirmMessage={`Remove service "${service.id}" from castle.yaml? Run a deploy afterward to tear down its unit.`}
       />
     </div>
   )

app/src/components/detail/fields.tsx

@@ -122,18 +122,27 @@ export function FormFooter({
   onSave,
   onDelete,
   deleteLabel,
+  confirmMessage,
+  deleteBlocked,
 }: {
   saving: boolean
   saved: boolean
   onSave: () => void
   onDelete?: () => void
   deleteLabel: string
+  confirmMessage?: string
+  /** When set, removal is disallowed and this reason is shown instead of the button. */
+  deleteBlocked?: string
 }) {
   return (
     <div className="flex items-center justify-between pt-3 border-t border-[var(--border)]">
-      {onDelete ? (
+      {deleteBlocked ? (
+        <span className="text-xs text-amber-400">{deleteBlocked}</span>
+      ) : onDelete ? (
         <button
-          onClick={onDelete}
+          onClick={() => {
+            if (window.confirm(confirmMessage ?? `${deleteLabel}?`)) onDelete()
+          }}
           className="flex items-center gap-1.5 text-xs text-red-400 hover:text-red-300"
         >
           <Trash2 size={12} /> {deleteLabel}