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/ui/icons/icons.go

@@ -11,6 +11,7 @@ type Set struct {
 	Repo       string
 	Encrypted  string // an encrypted file (SOPS)
 	PlainFile  string // a plain text secrets file (.env)
+	Spring     string // a Spring Boot config file
 	Note       string // has a note (lazysecrets list)
 }
 
@@ -25,6 +26,7 @@ var NerdFont = Set{
 	Repo:       "\U000F02A2", // md-git
 	Encrypted:  "\U000F033E", // md-lock
 	PlainFile:  "\U000F0214", // md-file
+	Spring:     "\U000F032A", // md-leaf
 	Note:       "\U000F09ED",
 }