feat(vscode): add JLink flash/debug tasks and VSCode config

- tasks.json: Build + Flash/Reset/Erase via JLink Commander
- launch.json: cortex-debug J-Link debug configuration
- flash.jlink: JLink Commander script for automated flashing
- extensions.json: recommended VSCode extensions
- .gitignore: remove .vscode/ exclusion (template needs these files)

.vscode/launch.json

@@ -0,0 +1,27 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "cwd": "${workspaceFolder}",
+            "executable": "${workspaceFolder}/Build/Debug/Application/Application.elf",
+            "name": "Debug with J-Link",
+            "request": "launch",
+            "type": "cortex-debug",
+            "runToEntryPoint": "main",
+            "showDevDebugOutput": "none",
+            "servertype": "jlink",
+            "device": "GD32E230F8",
+            "interface": "swd",
+            "svdFile": "${workspaceFolder}/GD32E230.svd",
+            "liveWatch": {
+                "enabled": true,
+                "samplesPerSecond": 1
+            },
+            "preLaunchTask": "Build",
+            "preRestartCommands": [
+                "load",
+                "continue"
+            ]
+        }
+    ]
+}