feat: accept --global on :report subcommands

Every `:report` subcommand now recognizes `--global` as a scope selector that limits the report to globally-configured properties, including in JSON form via `--global --format json`. Previously this combination was rejected because `--global` was treated as an info flag, conflicting with `--format`. The shared `common.ParseReportArgs` helper now returns a `ReportArgs` struct exposing the parsed scope; each Go and bash report selects a global-only flag map when scope is global, and skips per-app verification.

tests/unit/certs.bats

@@ -41,6 +41,20 @@ teardown() {
   assert_output "$help_output"
 }
 
+@test "(certs:report) --global --format json" {
+  run /bin/bash -c "dokku certs:report --global --format json | jq -e ."
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "{}"
+
+  run /bin/bash -c "dokku certs:report --global"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains "global ssl information"
+}
+
 @test "(certs) certs:add" {
   run /bin/bash -c "dokku certs:add $TEST_APP $BATS_TMPDIR/tls/server.crt $BATS_TMPDIR/tls/server.key"
   echo "output: $output"