fix: resolve all revive linter issues

Added missing package comments:
- cmd/secret/main.go
- internal/cli/cli.go
- internal/secret/constants.go
- internal/vault/management.go
- pkg/bip85/bip85.go

Fixed comment format issues for exported items:
- EnvStateDir, EnvMnemonic, EnvUnlockPassphrase, EnvGPGKeyID in constants.go
- Metadata, UnlockerMetadata, SecretMetadata, Configuration in metadata.go
- AppBIP39, AppHDWIF, AppXPRV in bip85.go

Replaced unused parameters with underscore (_):
- generate.go:39 - parameter 'args'
- init.go:30 - parameter 'args'
- unlockers.go:39,77,102 - parameter 'args' or 'cmd'
- vault.go:37 - parameter 'args'
- management.go:34 - parameter 'target'

internal/cli/generate.go

@@ -36,7 +36,7 @@ func newGenerateMnemonicCmd() *cobra.Command {
 		Long: `Generate a cryptographically secure random BIP39 ` +
 			`mnemonic phrase that can be used with 'secret init' ` +
 			`or 'secret import'.`,
-		RunE: func(cmd *cobra.Command, args []string) error {
+		RunE: func(cmd *cobra.Command, _ []string) error {
 			cli := NewCLIInstance()
 
 			return cli.GenerateMnemonic(cmd)