chore: open-source release-prep (udev flag, SPDX headers, boolean style)

Three release cleanups, all behavior-preserving for my machines:

- Gated the Logitech BRIO udev rule behind INSTALL_DEVICE_UDEV_RULES (default yes, opt-out), so the device-specific rule is off for anyone without that hardware. Added the config read, validation, and a conf.example entry.
- Added a GPL-3.0-or-later SPDX-License-Identifier header after the shebang of all 24 shell scripts in the repo.
- Standardized boolean conditionals on the explicit [ "$var" = "true" ] form, replacing the bare `if $var` idiom. The STEPS function-dispatch is left alone, since it runs a function name rather than testing a boolean.

1 files changed, 5 insertions, 0 deletions

diff --git a/archsetup.conf.example b/archsetup.conf.example
index 962d05f..82f6898 100644
--- a/archsetup.conf.example
+++ b/archsetup.conf.example
@@ -39,6 +39,11 @@
 # Set to "no" to skip it (no AI tooling, avoids the curl-pipe-bash step).
 #INSTALL_CLAUDE_CODE=yes
 
+# Install device-specific udev rules (default: yes)
+# Currently the Logitech BRIO webcam auto-configuration rule. These target
+# specific hardware; set to "no" if your machine doesn't have those devices.
+#INSTALL_DEVICE_UDEV_RULES=yes
+
 # System locale (default: prompt if not already configured)
 # Common options: en_US.UTF-8, en_GB.UTF-8, de_DE.UTF-8, es_ES.UTF-8,
 #                 fr_FR.UTF-8, pt_BR.UTF-8, ja_JP.UTF-8, zh_CN.UTF-8