build: 对齐模板工具链与 .vscode，APP 迁移 Bootloader 布局(0x08002000/54K)

工程编译与开发环境（参照 gd32e23x_template_cmake_vscode 模板）
- cmake/arm-none-eabi-gcc.cmake：硬编码工具链路径改为 GD32_GCC_BIN
  环境变量 / -DTOOLCHAIN_DIRECTORY 参数，与模板逐字一致
- .vscode：launch/tasks/settings/extensions 对齐模板，烧录与调试全部
  读取 GD32_GCC_BIN / GD32_OPENOCD_BIN / GD32_OPENOCD_SCRIPTS 环境变量；
  新增 J-Link 调试配置与 flash/reset/erase.jlink 脚本
- CMakeLists.txt：POST_BUILD 增加 Application/Application.hex 生成
  （J-Link 烧录脚本 loadfile 依赖）
- 验证：Debug / Release 编译通过（本机 ARM GCC 15.2.1）

Bootloader 布局适配（与旧版独立镜像不兼容，升级需整片烧录一次）
- LD/gd32e23x_flash.ld：FLASH ORIGIN=0x08002000, LENGTH=54K
- Src/system_gd32e23x.c：VECT_TAB_OFFSET=0x2000——Bootloader 不写
  VTOR，APP 必须自设向量表，否则中断落回 Bootloader 向量表
- 验证：.vectors 链接于 0x08002000，固件 12164B（54KB 上限 22%）

驱动修复
- Src/ldc1612.c：ldc1612_config_single_channel 各步骤 I2C 写入检查
  返回值，失败立即返回错误（原审查项 L3）

文档
- README：重写本地编译/烧录/调试说明，新增"固件布局与 Bootloader"章节

.vscode/launch.json

@@ -9,20 +9,19 @@
             "type": "cortex-debug",
             "runToEntryPoint": "main",
             "showDevDebugOutput": "none",
-            "gdbPath": "${workspaceFolder}/Toolchain/xpack-arm-none-eabi-gcc-11.3.1-1.1/bin/arm-none-eabi-gdb.exe",
+            "gdbPath": "${env:GD32_GCC_BIN}/arm-none-eabi-gdb.exe",
             "servertype": "openocd",
-            "serverpath": "${workspaceFolder}/Toolchain/xpack-openocd-0.11.0-3/bin/openocd.exe",
+            "serverpath": "${env:GD32_OPENOCD_BIN}/openocd.exe",
             "svdFile": "${workspaceFolder}/GD32E230.svd",
-            "liveWatch": {
-                "enabled": true,
-                "samplesPerSecond": 1
-            },
             "configFiles": [
-                "${workspaceFolder}/Toolchain/xpack-openocd-0.11.0-3/scripts/target/openocd_gdlink_gd32e23x.cfg"
+                "${env:GD32_OPENOCD_SCRIPTS}/${config:gd32.openocd.targetConfig}"
             ],
             "serverArgs": [
-                "-s", "${workspaceFolder}/Toolchain/xpack-openocd-0.11.0-3/scripts"
+                "-s", "${env:GD32_OPENOCD_SCRIPTS}"
             ],
+            "env": {
+                "OPENOCD_SCRIPTS": "${env:GD32_OPENOCD_SCRIPTS}"
+            },
             "searchDir": [
                 "${workspaceFolder}"
             ],
@@ -30,7 +29,30 @@
             "preRestartCommands": [
                 "load",
                 "continue"
-            ],
+            ]
         },
+        {
+            "cwd": "${workspaceFolder}",
+            "executable": "${workspaceFolder}/Build/Debug/Application/Application.elf",
+            "name": "Debug with J-Link",
+            "request": "launch",
+            "type": "cortex-debug",
+            "runToEntryPoint": "main",
+            "showDevDebugOutput": "none",
+            "gdbPath": "${env:GD32_GCC_BIN}/arm-none-eabi-gdb.exe",
+            "servertype": "jlink",
+            "device": "${config:gd32.jlink.device}",
+            "interface": "${config:gd32.jlink.interface}",
+            "svdFile": "${workspaceFolder}/GD32E230.svd",
+            "liveWatch": {
+                "enabled": true,
+                "samplesPerSecond": 1
+            },
+            "preLaunchTask": "Build",
+            "preRestartCommands": [
+                "load",
+                "continue"
+            ]
+        }
     ]
-}
+}