Add KVM scripts for Mac/Nobara switching

- to_mac.sh: Switch from Nobara to Mac (monitor USB-C, peripherals Ch3)
- to_nobara.sh: Switch from Mac to Nobara (monitor HDMI2, peripherals Ch2)
- README.md: Setup instructions for both machines

Uses DDC/CI for monitor and HID++ for Logitech Bolt peripherals.

scripts/kvm/README.md

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+# KVM Switch: Mac ↔ Nobara
+
+Software KVM to switch Dell U3821DW monitor and Logitech MX peripherals between Mac and Nobara.
+
+## Hardware
+
+- **Monitor:** Dell U3821DW (USB-C to Mac, HDMI 2 to Nobara)
+- **Keyboard:** Logitech MX Keys S
+- **Mouse:** Logitech MX Master 3S
+- **Bolt #1:** Connected directly to Nobara
+- **Bolt #2:** Connected to Dell monitor USB hub (routes to Mac via USB-C)
+
+## Channel Setup
+
+| Channel | Code | Connection | Computer |
+|---------|------|------------|----------|
+| 2 | 0x01 | Bolt #1 | Nobara |
+| 3 | 0x02 | Bolt #2 (via monitor) | Mac |
+
+## Mac Setup
+
+### Prerequisites
+```bash
+# Install m1ddc (DDC control for Apple Silicon)
+brew install m1ddc
+
+# Install hidapitester
+curl -sL https://github.com/todbot/hidapitester/releases/latest/download/hidapitester-macos-arm64.zip -o /tmp/hidapitester.zip
+unzip -o /tmp/hidapitester.zip -d ~/bin/
+chmod +x ~/bin/hidapitester
+```
+
+### Install Script
+```bash
+mkdir -p ~/scripts
+cp to_nobara.sh ~/scripts/
+chmod +x ~/scripts/to_nobara.sh
+```
+
+### Keyboard Shortcut (Logi Options+)
+1. Logi Options+ → MX Keys S → Smart Actions
+2. Create action triggered by F12
+3. Action: Open File → ~/scripts/to_nobara.sh
+
+## Nobara Setup
+
+### Prerequisites
+```bash
+# Install ddcutil
+sudo dnf install -y ddcutil
+
+# Add user to i2c group (REBOOT REQUIRED)
+sudo usermod -aG i2c $USER
+
+# Install hidapitester
+mkdir -p ~/bin
+curl -sL https://github.com/todbot/hidapitester/releases/latest/download/hidapitester-linux-amd64.zip -o /tmp/hidapitester.zip
+unzip -o /tmp/hidapitester.zip -d ~/bin/
+chmod +x ~/bin/hidapitester
+rm /tmp/hidapitester.zip
+
+# Udev rule for non-root HID access
+echo 'SUBSYSTEM=="usb", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="c548", MODE="0666"' | \
+  sudo tee /etc/udev/rules.d/99-logitech-bolt.rules
+sudo udevadm control --reload-rules && sudo udevadm trigger
+```
+
+### Install Script
+```bash
+mkdir -p ~/scripts
+cp to_mac.sh ~/scripts/
+chmod +x ~/scripts/to_mac.sh
+```
+
+### Keyboard Shortcut (GNOME)
+1. Settings → Keyboard → Custom Shortcuts
+2. Add shortcut:
+   - Name: KVM to Mac
+   - Command: /home/USER/scripts/to_mac.sh
+   - Shortcut: F12
+
+## Pairing Peripherals
+
+Each device must be paired to BOTH Bolt receivers:
+
+### MX Master 3S / MX Keys S
+1. Press Easy-Switch button to select channel (2 for Nobara, 3 for Mac)
+2. Hold 3 seconds until LED blinks fast
+3. Use Logi Options+ (Mac) or Solaar (Linux) to complete pairing
+
+### Install Solaar (Linux)
+```bash
+sudo dnf install solaar
+solaar &
+# Click "Pair new device" while peripheral is blinking
+```
+
+## Troubleshooting
+
+### Monitor doesn't switch
+- Check DDC/CI is enabled: Monitor Menu → Others → DDC/CI → On
+- Mac: Ensure USB-C cable supports data (not video-only)
+- Linux: Ensure user is in i2c group and rebooted
+
+### Peripherals don't switch
+- Verify devices are paired to both Bolt receivers
+- Check device indices with: `solaar show` (Linux)
+- Device indices (0x01, 0x02) depend on pairing order
+
+### Find correct device indices
+```bash
+# On Linux with solaar
+solaar show
+
+# Or query via HID++
+hidapitester --vidpid 046d/c548 --list-detail
+```
+
+## DDC Input Codes (Dell U3821DW)
+
+| Input | Code |
+|-------|------|
+| HDMI 1 | 17 |
+| HDMI 2 | 18 |
+| USB-C | 27 |
+| DP 1 | 15 |
+| DP 2 | 16 |

scripts/kvm/to_mac.sh

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+#!/bin/bash
+# KVM Switch: Nobara → Mac
+# Switches monitor to USB-C and peripherals to Channel 3 (Mac Bolt via monitor hub)
+#
+# Channel setup:
+#   Channel 2 (0x01): Bolt #1 → Nobara
+#   Channel 3 (0x02): Bolt #2 → Mac (via monitor USB hub)
+
+set -e
+
+HIDAPITESTER="$HOME/bin/hidapitester"
+[ -x "$HIDAPITESTER" ] || HIDAPITESTER="/usr/local/bin/hidapitester"
+
+echo "Switching to Mac..."
+
+# 1. Switch Monitor to USB-C (Dell U3821DW input code: 27)
+echo "  Monitor -> USB-C..."
+if command -v ddcutil &>/dev/null; then
+    ddcutil setvcp 60 27 2>/dev/null || \
+        echo "  [WARN] Monitor switch failed (DDC/CI disabled or permissions issue)"
+else
+    echo "  [WARN] ddcutil not installed: sudo dnf install ddcutil"
+fi
+
+# 2. Switch Mouse (MX Master 3S) to Channel 3 (Mac Bolt)
+# Device index 0x01 - adjust if mouse was paired in different order
+echo "  Mouse -> Channel 3..."
+"$HIDAPITESTER" --vidpid 046d/c548 --usage 0x0001 --usagePage 0xff00 \
+    --open --length 7 --send-output 0x10,0x01,0x09,0x1b,0x02,0x00,0x00 2>/dev/null || \
+    echo "  [WARN] Mouse switch failed"
+
+# 3. Switch Keyboard (MX Keys S) to Channel 3 (Mac Bolt)
+# Device index 0x02 - adjust if keyboard was paired in different order
+echo "  Keyboard -> Channel 3..."
+"$HIDAPITESTER" --vidpid 046d/c548 --usage 0x0001 --usagePage 0xff00 \
+    --open --length 7 --send-output 0x10,0x02,0x09,0x1b,0x02,0x00,0x00 2>/dev/null || \
+    echo "  [WARN] Keyboard switch failed"
+
+echo "Done!"

scripts/kvm/to_nobara.sh

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+#!/bin/bash
+# KVM Switch: Mac → Nobara
+# Switches monitor to HDMI 2 and peripherals to Channel 2 (Nobara Bolt)
+#
+# Channel setup:
+#   Channel 2 (0x01): Bolt #1 → Nobara
+#   Channel 3 (0x02): Bolt #2 → Mac (via monitor USB hub)
+
+set -e
+
+HIDAPITESTER="$HOME/bin/hidapitester"
+
+echo "Switching to Nobara..."
+
+# 1. Switch Monitor to HDMI 2 (Dell U3821DW input code: 18)
+echo "  Monitor -> HDMI 2..."
+if ! m1ddc set input 18 2>/dev/null; then
+    echo "  [WARN] Monitor switch failed (DDC/CI disabled or not connected via USB-C)"
+fi
+
+# 2. Switch Mouse (MX Master 3S) to Channel 2 (Nobara Bolt)
+# Device index 0x01 - adjust if mouse was paired in different order
+echo "  Mouse -> Channel 2..."
+"$HIDAPITESTER" --vidpid 046d/c548 --usage 0x0001 --usagePage 0xff00 \
+    --open --length 7 --send-output 0x10,0x01,0x09,0x1b,0x01,0x00,0x00 2>/dev/null || \
+    echo "  [WARN] Mouse switch failed"
+
+# 3. Switch Keyboard (MX Keys S) to Channel 2 (Nobara Bolt)
+# Device index 0x02 - adjust if keyboard was paired in different order
+echo "  Keyboard -> Channel 2..."
+"$HIDAPITESTER" --vidpid 046d/c548 --usage 0x0001 --usagePage 0xff00 \
+    --open --length 7 --send-output 0x10,0x02,0x09,0x1b,0x01,0x00,0x00 2>/dev/null || \
+    echo "  [WARN] Keyboard switch failed"
+
+echo "Done!"