Rev 0.2: Major hardware improvements and production readiness

Hardware Improvements (Thanks to shx for schematic cleanup):
- Clean up schematic organization and structure
- Set CAN transceiver Silent pin to GND for stability
- Add status LEDs (yellow: 24V/5V/3.3V, green: MCU PB4)
- Replace jumpers with solder jumpers on bottom side
- Add jumpers to output PFETs for permanent-on without firmware
- Add robust test points for 5V/GND load testing
- Add optional heatsink for DC/DC converter on bottom
- Add 10µF capacitor for MCU on 3.3V rail

Component Optimizations:
- Replace 30kΩ with 33kΩ basic part for simplified BOM
- Change DC/DC feedback: 15.5kΩ15kΩ (new output: 5.1V)
- Upgrade CAN ESD protection: NUP2105LPESD1CAN
- Increase CAN termination resistor footprint: 04020603
- Switch USB hub supply from 5V to 3.3V per datasheet

Production Ready:
- Add all LCSC part numbers and rotations
- Generate complete production data package
- Improve PCB layout and button placement
- Create comprehensive changelog documentation

README.md

@@ -35,6 +35,7 @@ A universal interface board (HAT) for Raspberry Pi 4/5 and Radxa Rock 5B designe
     - [Component Sourcing](#component-sourcing)
   - [🛠️ Technical Specifications](#️-technical-specifications)
   - [📚 Additional Resources](#-additional-resources)
+  - [📝 Changelog](#-changelog)
   - [License](#license)
 
 <!-- /code_chunk_output -->
@@ -232,6 +233,10 @@ sensor_mcu: hat
 - [STM32G0 Reference Manual](https://www.st.com/resource/en/reference_manual/rm0454-stm32g0x0-advanced-armbased-32bit-mcus-stmicroelectronics.pdf)
 - [Katapult Firmware Flasher](https://github.com/Arksine/katapult)
 
+## 📝 Changelog
+
+For detailed information about changes and updates, see [CHANGELOG.md](CHANGELOG.md).
+
 ## License
 
 This project is licensed under the **Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License** (CC BY-NC-SA 4.0).