Optimize Signal Routing and Improve Schematic Design

### Description
The current schematic and PCB routing require optimization. Several signal paths between components and MCU pins are longer than necessary, which increases routing complexity and may affect signal integrity.

### Tasks
- Review the current schematic layout
- Reorganize component placement to shorten signal paths
- Reduce unnecessary crossings and long connections
- Improve logical grouping of related components
- Verify correct pin assignments for optimal routing
- Simplify signal flow between MCU, multiplexer, and input devices

### Goals
- Shorter and cleaner signal routes
- Improved schematic readability
- Easier PCB routing
- Reduced design complexity

Start by reviewing the current schematic and PCB routing for the MCU, multiplexer, and input devices. Reorganize placement and connections to reduce crossings and unnecessary path length, verify pin assignments, and confirm that the resulting schematic is clearer and the PCB is easier to route.

Written by the indexing model from the issue text.