feat: decrypt Jasypt values in .env and Spring files

ENC(...) values are decrypted on reveal, copy or get with
jasypt-spring-boot's default algorithm (3.0+, PBEWITHHMACSHA512ANDAES_256).

- The password is, as in Spring, $JASYPT_ENCRYPTOR_PASSWORD, else the
  file's own jasypt.encryptor.password (JASYPT_ENCRYPTOR_PASSWORD in a
  .env), with ${VAR} and ${VAR:default} read from the environment.
- Errors say which password was used, or which one is missing.
- Secrets show a detail after their name: jasypt, or reference for a
  Spring ${VAR}; also in Go to and Favourites.
- A .env whose values are all Jasypt isn't marked as plain text in git.

internal/provider/provider.go

@@ -133,6 +133,7 @@ type Object struct {
 	Type        ObjectType
 	ID          string
 	Name        string
+	Detail      string // shown after the name, e.g. "jasypt" for how its value is kept
 	Version     string
 	Enabled     *bool
 	Updated     time.Time