feat: add terminal bell sound and visual flash notifications

Implement system bell (BEL / \x07) support with configurable audio and visual feedback for the terminal. Add new settings to control bell behavior:
- snow-cli.bell.enabled: toggle bell notifications
- snow-cli.bell.volume: adjust audio volume (0.0-1.0)
- snow-cli.bell.sound: choose from beep, ding, chime, pluck, blip, or none
- snow-cli.bell.visualFlash: enable/disable visual flash overlay

Features include:
- Web Audio API synthesis with multiple sound styles
- Visual flash animation on terminal container
- Rate limiting to prevent bell spam (80ms minimum interval)
- AudioContext suspension handling for webview compatibility
- Hot-reload configuration without terminal restart
- Graceful fallback when audio is unavailable

Bump version to 0.4.23.

Author: MayDay-wpf

.github/workflows/build_vsix.yml

@@ -65,7 +65,7 @@ jobs:
 
             ### What's New
 
-            - Add AI-generated git commit message feature
+            - Fix the problem of not being able to trigger the system ringtone and add relevant settings
 
             ### Installation
 

VSIX/package-lock.json

@@ -2,7 +2,7 @@
 	"name": "snow-cli",
 	"displayName": "Snow CLI",
 	"description": "Snow AI CLI with ACE Code Search - Intelligent code navigation and search powered by AI",
-	"version": "0.4.22",
+	"version": "0.4.23",
 	"publisher": "mufasa",
 	"repository": {
 		"type": "git",
@@ -91,6 +91,44 @@
 					"type": "boolean",
 					"default": false,
 					"description": "Enable Git Blame annotations. Shows commit info (author, time, message) on the current line, similar to GitLens."
+				},
+				"snow-cli.bell.enabled": {
+					"type": "boolean",
+					"default": true,
+					"description": "Enable terminal bell (BEL / \\x07) notifications. When disabled, both audio and visual feedback are suppressed."
+				},
+				"snow-cli.bell.volume": {
+					"type": "number",
+					"default": 0.5,
+					"minimum": 0,
+					"maximum": 1,
+					"description": "Terminal bell volume (0.0 - 1.0). Set to 0 to mute audio while still allowing visual flash."
+				},
+				"snow-cli.bell.sound": {
+					"type": "string",
+					"default": "beep",
+					"enum": [
+						"beep",
+						"ding",
+						"chime",
+						"pluck",
+						"blip",
+						"none"
+					],
+					"enumDescriptions": [
+						"Short 800Hz sine beep (default classic terminal bell)",
+						"Bright triangle-wave ding",
+						"Two-tone descending chime",
+						"Soft sawtooth pluck",
+						"Quick high-frequency blip",
+						"No sound (visual flash only)"
+					],
+					"description": "Bell sound style. Use 'none' to disable audio while keeping visual flash enabled."
+				},
+				"snow-cli.bell.visualFlash": {
+					"type": "boolean",
+					"default": true,
+					"description": "Show a brief visual flash overlay on the terminal panel when the bell rings."
 				}
 			}
 		},

VSIX/package.json

@@ -216,6 +216,40 @@ body {
 	outline-offset: -2px;
 }
 
+#terminal-container::after {
+	content: '';
+	position: absolute;
+	inset: 0;
+	z-index: 5;
+	pointer-events: none;
+	background: rgba(255, 255, 255, 0);
+	border: 0 solid rgba(255, 255, 255, 0);
+	box-sizing: border-box;
+	opacity: 0;
+}
+
+#terminal-container.bell-flash::after {
+	animation: terminal-bell-flash 320ms ease-out;
+}
+
+@keyframes terminal-bell-flash {
+	0% {
+		opacity: 1;
+		background: rgba(255, 255, 255, 0.18);
+		border: 3px solid rgba(255, 255, 255, 0.85);
+	}
+	60% {
+		opacity: 0.6;
+		background: rgba(255, 255, 255, 0.05);
+		border: 3px solid rgba(255, 255, 255, 0.4);
+	}
+	100% {
+		opacity: 0;
+		background: rgba(255, 255, 255, 0);
+		border: 3px solid rgba(255, 255, 255, 0);
+	}
+}
+
 #terminal-container.terminal-error {
 	color: var(--terminal-error);
 	padding: 20px;