feat: Docker Compose files in repos

compose.yaml, docker-compose.yml and their variants tracked by git are
listed under Repos, their services' environment variables as secrets,
named service.VAR.

- environment as a map or a list, and <<: *anchors shared between
  services; the secret patterns pick the keys, the rest hidden, with
  compose.secretPatterns for compose files' own.
- ${VAR}, $VAR, ${VAR:?…} and variables without a value are marked as
  references; docker-compose.example.yml and the like are hidden.
- Jasypt values decrypt with the service's JASYPT_ENCRYPTOR_PASSWORD.
- A blue Docker icon, themeable with composeColor.

internal/provider/repo/spring_test.go

@@ -30,7 +30,7 @@ func TestIsSpring(t *testing.T) {
 	}
 }
 
-func springNames(keys []springKey) map[string]string {
+func springNames(keys []configKey) map[string]string {
 	out := map[string]string{}
 	for _, k := range keys {
 		out[k.name] = k.value