feat: Spring Boot config files in repos

application*.properties/.yml and bootstrap* files tracked by git are
listed under Repos, with their secret-looking keys as secrets.

- Keys whose name ends like a secret (password, secret, token, key, …)
  or whose value looks like one (Jasypt ENC(...), a URL or connection
  string with a password) are listed; providers.repos.spring.keys and
  .values replace the patterns, also in a repo's .lazysecrets.yaml.
- A file's details count the keys left out; ${VAR} values are marked
  as references, and a tracked file is only marked red when a listed
  value is in plain text.
- Later YAML/properties documents name their keys after the profile:
  spring.datasource.password (prod).
- Maven's @placeholders@ parse; Argo CD's applications.yaml and Helm
  templates aren't Spring files.
- A green leaf icon, themeable with springColor.

internal/config/config_test.go

@@ -84,6 +84,7 @@ func TestLoadRejectsMistakes(t *testing.T) {
 		"workspace":  "sharing:\n  key: \"{{secrets/team/env-share}}\"\n",
 		"short keys": "sharing:\n  keyRules:\n    minLength: 8\n",
 		"classes":    "sharing:\n  keyRules:\n    minClasses: 5\n",
+		"regexp":     "providers:\n  repos:\n    spring:\n      keys: [\"(pass\"]\n",
 	} {
 		if _, err := LoadAll([]string{write(t, content)}); err == nil {
 			t.Errorf("%s: no error", name)