UA1ZBE Custom Firmware v1.0

Features:
- VFO mode with direct frequency input
- POCSAG decoder (512/1200 baud) with BCH(31,21) correction
- Full-screen Spectrum analyzer
- FM Radio receiver
- RSSI signal indicator overlay
- Custom boot splash (UA1ZBE / POCSAG pager / build date)

Architecture:
- app/mode.c — mode dispatcher (VFO/POCSAG/Spectrum/FM)
- app/boot_splash.c — 2-second boot splash
- app/pocsag/ — POCSAG decoder + BCH correction
- app/display_rssi.c — RSSI indicator
- main.c — entry point with custom init
- syscalls.c — bare-metal _sbrk stub

Build: arm-none-eabi-gcc -Os -flto -Wall -Werror -Wextra
Size: 57.9KB Flash / 3.6KB RAM

Controls:
- 0-9: Direct frequency input (VFO)
- SK2: POCSAG mode
- SK1: Spectrum analyzer
- 0: FM Radio
- EXIT: Return to VFO
- F/*: Toggle 512/1200 baud (in POCSAG)

external/CMSIS_5/docker/rtebuild/gcc.rtebuild

@@ -0,0 +1,27 @@
+toolchain:
+  GCC:
+    env:
+      PATH     : [ "/opt/gcc-arm-none-eabi-10-2020-q4-major/bin" ]
+    rte:
+      Tcompiler: "GCC"
+      Toptions : ""
+    ccompiler:
+      cmd     : "arm-none-eabi-gcc"
+      cmdfile : "@\""
+      input   : "\""
+      output  : "-o \""
+      include : "-I\""
+      define  : "-D"
+    assembler:
+      cmd     : "arm-none-eabi-gcc"
+      cmdfile : "@\""
+      input   : "\""
+      output  : "-o \""
+      include : "-I\""
+      define  : "-D"
+    linker:
+      cmd     : "arm-none-eabi-gcc"
+      cmdfile : "@\""
+      input   : "\""
+      output  : "-o \""
+      script  : "-T \""