feat(school_stm32): 添加基础的 STM32F103RCT6 项目结构

- 创建了项目的基本目录结构和文件
- 添加了 CMakeLists.txt 和 Makefile 构建配置
- 创建了 main.c 文件，实现了简单的 LED 闪烁和按键检测功能
- 集成了 SEGGER RTT 库
- 添加了 .gitignore 文件，排除了不必要的生成文件

libs/SEGGER_RTT/README.md

@@ -0,0 +1,24 @@
+RTT
+===
+
+SEGGER RTT Sources
+
+https://www.segger.com/products/debug-probes/j-link/technology/about-real-time-transfer  
+https://wiki.segger.com/RTT
+
+## Included files
+
+  * `RTT/`
+    * `SEGGER_RTT.c`               - Main module for RTT.
+    * `SEGGER_RTT.h`               - Main header for RTT.
+    * `SEGGER_RTT_ASM_ARMv7M.S`    - Assembly-optimized implementation of RTT functions for ARMv7M processors.
+    * `SEGGER_RTT_Printf.c`        - Simple implementation of printf (`SEGGER_RTT_Printf()`) to write formatted strings via RTT.
+  * `Syscalls/`
+    * `SEGGER_RTT_Syscalls_*.c`    - Low-level syscalls to retarget `printf()` to RTT with different toolchains.
+  * `Config/`
+    * `SEGGER_RTT_Conf.h`          - RTT configuration file.
+  * `Examples/`
+    * `Main_RTT_InputEchoApp.c`    - Example application which echoes input on Channel 0.
+    * `Main_RTT_MenuApp.c`         - Example application to demonstrate RTT bi-directional functionality.
+    * `Main_RTT_PrintfTest.c`      - Example application to test RTT's simple printf implementation.
+    * `Main_RTT_SpeedTestApp.c`    - Example application to measure RTT performance. (Requires embOS)