docs: update CHANGELOG.md v0.2 with all current changes

[Copilot]

CHANGELOG.md v0.2 section was incomplete, missing a significant number of changes introduced since its last update.

Added entries

• WiFi: wifi-networkmanager-p2p.conf (disable Wi-Fi Direct), ccm/cmac kernel modules loaded at boot for WPA auth
• NTP/Chrony: new chrony.conf, NET_NTP_STATIC_SERVER config param, conditional installation and config processing
• GRUB: GRUB_KERNEL_CMDLINE config param, set-grub-kernel-cmdline.sh sourcing it
• Automated install: autoinstall.yaml multi-user (admin + user1), late-commands for script deployment and gnome-initial-setup removal, runcmd for step1 auto-execution
• Network: netplan-dns-override-part.yaml fragment (appended in installer-step2)
• Docs: CONFIG.md reference

Changed entries

• Service management: systemd-hibernate-clear/resume.service masked at system + user level; USBGuard GNOME integration via gsettings; user-disable-services.desktop uses absolute path with [USER_ID] placeholder
• Network hardening: DNS DHCP override moved from 02-net-if-config.yaml → netplan-dns-override-part.yaml; 600 root:root on NetworkManager conf files
• Application security: all firefox-global.js pref() calls now use locked flag; firefox-global.js permissions set to 644
• Configuration: GRUB_KERNEL_CMDLINE and NET_NTP_STATIC_SERVER added to config.sh
• Installer: systemctl daemon-reload at end of step1; netplan DNS fragment appended at end of step2

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[Copilot]

Pull request overview

This PR completes the CHANGELOG.md v0.2 section by adding 65+ missing entries that document changes introduced since the last update. The update follows the Keep a Changelog format with categorized subsections under "Added" and "Changed" sections.

Changes:

• Added comprehensive documentation for WiFi P2P configuration, NTP/Chrony setup, GRUB kernel cmdline customization, automated installation enhancements, network DNS override fragments, and CONFIG.md reference
• Updated entries for service management (hibernation prevention, USBGuard integration), network hardening (DNS override relocation, NetworkManager permissions), Firefox security (locked preferences), configuration parameters, and installer improvements
• Organized all entries into logical feature categories (WiFi, NTP/Chrony, GRUB, Automated Installation, Network, Documentation, Service Management, Application Security, Configuration, Installer)

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