feat: make the basic photo check the default, no blink needed

src/core/settings.h

@@ -30,7 +30,9 @@ struct Settings {
     // A /dev/video path, "auto", or for testing "file:<video>" and
     // "images:<directory>".
     QString camera = QStringLiteral("auto");
-    LivenessMode liveness = LivenessMode::Heavy;
+    // Basic by default: screens and phones are caught without asking for a
+    // blink. Strict adds the blink or head turn that stops a printed photo.
+    LivenessMode liveness = LivenessMode::Light;
     Strictness strictness = Strictness::Normal;
     // Only a face that looks at the screen with its eyes open counts.
     bool attention = true;

src/lib/config.sh

@@ -126,7 +126,7 @@ pfu_config_load() {
 	_pfu_kv_lookup "$PFU_CONFIG" Sudo no;             CFG_SUDO=no;     pfu_is_true "$PFU_KV_VALUE" && CFG_SUDO=yes
 	_pfu_kv_lookup "$PFU_CONFIG" Polkit no;           CFG_POLKIT=no;   pfu_is_true "$PFU_KV_VALUE" && CFG_POLKIT=yes
 
-	_pfu_kv_lookup "$PFU_SYSCONFIG" Liveness heavy;   CFG_LIVENESS="$PFU_KV_VALUE"
+	_pfu_kv_lookup "$PFU_SYSCONFIG" Liveness light;   CFG_LIVENESS="$PFU_KV_VALUE"
 	_pfu_kv_lookup "$PFU_SYSCONFIG" Camera auto;      CFG_CAMERA="$PFU_KV_VALUE"
 	return 0
 }

src/lib/menu.sh

@@ -260,7 +260,7 @@ PFU_SETTINGS=(
 	"user|ScanOnLock|bool|no|Look right after the screen locks"
 	"pam|sudo|bool|no|Use for sudo in a terminal"
 	"pam|polkit-1|bool|no|Use for admin prompts"
-	"sys|Liveness|choice|heavy|Photo check|heavy,light,off"
+	"sys|Liveness|choice|light|Photo check|light,heavy,off"
 	"sys|Strictness|choice|normal|How closely a face has to match|normal,strict,relaxed"
 	"sys|Attention|bool|yes|Only while looking at the screen"
 	"sys|Camera|camera|auto|Camera"