Allow uppercase letters in secret names (closes #2)

The isValidSecretName() regex only allowed lowercase letters [a-z], rejecting
valid secret names containing uppercase characters (e.g. AWS access key IDs).

Changed regex from ^[a-z0-9\.\-\_\/]+$ to ^[a-zA-Z0-9\.\-\_\/]+$ and added
tests for uppercase secret names in both vault and secret packages.

internal/vault/secrets.go

@@ -67,7 +67,7 @@ func (v *Vault) ListSecrets() ([]string, error) {
 	return secrets, nil
 }
 
-// isValidSecretName validates secret names according to the format [a-z0-9\.\-\_\/]+
+// isValidSecretName validates secret names according to the format [a-zA-Z0-9\.\-\_\/]+
 // but with additional restrictions:
 // - No leading or trailing slashes
 // - No double slashes
@@ -93,7 +93,7 @@ func isValidSecretName(name string) bool {
 	}
 
 	// Check the basic pattern
-	matched, _ := regexp.MatchString(`^[a-z0-9\.\-\_\/]+$`, name)
+	matched, _ := regexp.MatchString(`^[a-zA-Z0-9\.\-\_\/]+$`, name)
 
 	return matched
 }

internal/vault/secrets_name_test.go

@@ -0,0 +1,42 @@
+package vault
+
+import "testing"
+
+func TestIsValidSecretNameUppercase(t *testing.T) {
+	tests := []struct {
+		name  string
+		valid bool
+	}{
+		// Lowercase (existing behavior)
+		{"valid-name", true},
+		{"valid.name", true},
+		{"valid_name", true},
+		{"valid/path/name", true},
+		{"123valid", true},
+
+		// Uppercase (new behavior - issue #2)
+		{"Valid-Upper-Name", true},
+		{"2025-11-21-ber1app1-vaultik-test-bucket-AKI", true},
+		{"MixedCase/Path/Name", true},
+		{"ALLUPPERCASE", true},
+		{"ABC123", true},
+
+		// Still invalid
+		{"", false},
+		{"invalid name", false},
+		{"invalid@name", false},
+		{".dotstart", false},
+		{"/leading-slash", false},
+		{"trailing-slash/", false},
+		{"double//slash", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isValidSecretName(tt.name)
+			if result != tt.valid {
+				t.Errorf("isValidSecretName(%q) = %v, want %v", tt.name, result, tt.valid)
+			}
+		})
+	}
+}