fix: match docker options by shell word when removing

Options drained out of the pre-0.38.0 `DOCKER_OPTIONS_<PHASE>` files were copied verbatim rather than re-serialized the way `docker-options:add` stores them, so `docker-options:remove` compared the canonical string it builds against a stored value that could never match it and exited successfully without removing anything. Removal now matches stored options by shell word, and stored options are rewritten into the canonical form once on upgrade, which additionally splits an entry that carried several flags on a single line into one entry per flag so a single flag can be removed and so the readers that match on a flag prefix see one value per entry. The leftover `.migrated` sentinel drain is restored to running ahead of the global short-circuit that had made it unreachable, and the plugin's Go tests are added to the test target that had never run them.

tests/unit/docker-options.bats

@@ -441,6 +441,47 @@ teardown() {
   assert_output_contains "--link foo" 0
 }
 
+@test "(docker-options:remove) removes an option stored in the pre-0.38.25 unquoted form" {
+  # Options drained out of a legacy DOCKER_OPTIONS_<PHASE> file by
+  # releases before 0.38.26 were copied verbatim, so a value holding
+  # shell metacharacters sits in the property store unquoted. Seed that
+  # state directly - the add path always canonicalizes, so it cannot
+  # produce it.
+  run /bin/bash -c "dokku docker-options:add $TEST_APP deploy \"-v /tmp/keep:/keep\""
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  legacy_option='--group-add $(getent group docker | cut -d: -f3)'
+  property_file="/var/lib/dokku/config/docker-options/$TEST_APP/_default_.deploy"
+  run /bin/bash -c "printf '%s\n-v /tmp/keep:/keep\n' '$legacy_option' | sudo tee $property_file"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "sudo chown dokku:dokku $property_file"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku docker-options:list $TEST_APP --phase deploy"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output_contains "$legacy_option"
+
+  run /bin/bash -c "dokku docker-options:remove $TEST_APP deploy '$legacy_option'"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku docker-options:list $TEST_APP --phase deploy"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "-v /tmp/keep:/keep"
+}
+
 @test "(docker-options) dockerfile build skips unsupported flags from multi-flag input" {
   run /bin/bash -c "dokku docker-options:add $TEST_APP build --build-arg PAYPAL_CLIENT_ID=abc --link postgres"
   echo "output: $output"