fix: ServerSideApply on argocd Application to prune stale fields

argocd was originally helm-installed by hand before ArgoCD existed to
manage it; client-side 3-way merge apply can't prune fields it never
saw in a last-applied-configuration, so a later chart bump left a stale
args on repo-server's copyutil init container (old shell-string command
lingering alongside the new plain cp command) -> cp got 4 args instead
of 3 -> 'No such file or directory' -> CrashLoopBackOff -> Degraded.

Same bug class as envoy-gateway (020b248). ServerSideApply=true tracks
field ownership properly and prunes the stray field on next sync.

bootstrap/apps/argocd.yaml

@@ -20,3 +20,12 @@ spec:
   destination:
     server: https://kubernetes.default.svc
     namespace: argocd
+  # ArgoCD was originally `helm install`ed by hand before ArgoCD existed to
+  # manage it (see README Phase 3), so client-side 3-way merge apply can't
+  # see/prune fields from that pre-existing object — left a stale `args` on
+  # argocd-repo-server's copyutil init container after a later chart bump,
+  # crashlooping it (same bug class as envoy-gateway, see 020b248).
+  # ServerSideApply properly tracks field ownership and prunes it.
+  syncPolicy:
+    syncOptions:
+      - ServerSideApply=true