Rename udev rules file and update documentation

- Renamed udev rules file from 99-vpc.rules to 70-vpc.rules for better priority
- Updated all references to the file in Makefile and documentation
- Added instructions for manually creating udev rules when using precompiled binaries
- Improved installation instructions for both Windows and Linux platforms

TECHNICAL.md

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+# OpenVPC Shift Tool - Technical Documentation
+
+This document provides technical details about the OpenVPC Shift Tool application, its architecture, and how it works internally.
+
+## Architecture Overview
+
+The application is built using Rust with the following main components:
+
+1. **GUI Layer**: Uses the `eframe` crate (egui) for cross-platform GUI
+2. **HID Communication**: Uses the `hidapi` crate to communicate with VirPil devices
+3. **Configuration Management**: Uses the `fast_config` crate for saving/loading settings
+4. **Worker Thread**: Background thread that handles device communication
+
+## Core Components
+
+### Main Application Structure
+
+The main application is represented by the `ShiftTool` struct in `src/main.rs`, which contains:
+
+- State management
+- Device list
+- Shared state between UI and worker thread
+- Configuration data
+
+### Modules
+
+- **about.rs**: Contains application information and about screen text
+- **config.rs**: Configuration data structures and serialization
+- **device.rs**: Device representation and management
+- **hid_worker.rs**: Background worker thread for HID communication
+- **state.rs**: Application state enum
+- **ui.rs**: User interface drawing and event handling
+- **util.rs**: Utility functions and constants
+
+## Data Flow
+
+1. The application scans for VirPil devices (vendor ID 0x3344)
+2. User selects source and receiver devices in the UI
+3. When "Start" is clicked, a worker thread is spawned
+4. The worker thread:
+   - Opens connections to all configured devices
+   - Reads input from source devices
+   - Applies logical operations based on configuration
+   - Writes the resulting shift state to receiver devices
+5. Shared state (protected by mutexes) is used to communicate between the UI and worker thread
+
+## Device Communication
+
+### Device Detection
+
+Devices are detected using the HID API, filtering for VirPil's vendor ID (0x3344). The application creates `VpcDevice` objects for each detected device, which include:
+
+- Vendor ID and Product ID
+- Device name and firmware version
+- Serial number
+- Usage page/ID
+
+### HID Protocol
+
+The application supports different report formats based on device firmware versions. The worker thread:
+
+1. Reads HID reports from source devices
+2. Extracts button states from the reports
+3. Applies logical operations (OR, AND, XOR) to combine states
+4. Formats the combined state into HID reports
+5. Sends the reports to receiver devices
+
+## Configuration
+
+Configuration is stored in JSON format using the `fast_config` crate. The configuration includes:
+
+- Source devices (vendor ID, product ID, serial number, enabled bits)
+- Receiver devices (vendor ID, product ID, serial number, enabled bits)
+- Shift modifiers (logical operations for each bit)
+
+## Threading Model
+
+The application uses a main UI thread and a separate worker thread:
+
+1. **Main Thread**: Handles UI rendering and user input
+2. **Worker Thread**: Performs HID communication in the background
+
+Thread synchronization is achieved using:
+- `Arc<Mutex<T>>` for shared state
+- `Arc<(Mutex<bool>, Condvar)>` for signaling thread termination
+
+## Linux-Specific Features
+
+On Linux, the application requires udev rules to access HID devices without root privileges. The rule is installed to `/etc/udev/rules.d/70-vpc.rules` and contains:
+
+```
+# Virpil Control devices
+SUBSYSTEM=="usb", ATTRS{idVendor}=="3344", TAG+="uaccess", GROUP:="input"
+```
+
+## Building and Deployment
+
+The application can be built using Cargo:
+
+```bash
+cargo build --release
+```
+
+A Makefile is provided for easier installation on Linux, which:
+1. Builds the application
+2. Installs the binary to `/usr/local/bin`
+3. Installs udev rules to `/etc/udev/rules.d/`
+
+## Future Development
+
+Potential areas for enhancement:
+- Support for additional device types
+- More complex logical operations
+- Custom button mapping
+- Profile management
+- Integration with game APIs