Add GitHub release update check to Python GNOME and KDE KCM UIs

[Copilot]

On load, both the GNOME Python UI and the KDE KCM UI check the breezy-desktop GitHub releases and notify the user if a newer version is available.

Python GNOME UI

• New updatechecker.py: Fetches https://api.github.com/repos/wheaney/breezy-desktop/releases/latest in a background daemon thread using stdlib urllib (no new dependencies). Compares version tuples, strips v prefix from GitHub tags, and invokes a callback with the latest version string or None.
• window.ui: New GtkInfoBar (update_available_banner, message-type="info", initially hidden) displaying a plain update message with no button or link.
• window.py: Accepts version parameter; calls check_for_update() on init; callback uses GLib.idle_add to reveal the banner safely on the main thread.
• main.py: Passes self.version into BreezydesktopWindow.
• meson.build: Registers updatechecker.py as an installed source.

KDE KCM

• breezydesktopeffectkcm.ui: New labelUpdateAvailable QLabel (initially hidden, blue bold) inserted between labelGlobalWarning and the tab widget.
• breezydesktopeffectkcm.h/.cpp: New checkForUpdates() method using QNetworkAccessManager (async). On reply, parses version tuples with early-out on invalid components, logs network errors via qCDebug, and sets the label to a plain text message if the remote version is newer.
• CMakeLists.txt: Adds Qt6::Network to both find_package and target_link_libraries.

Both UIs display a plain message — "A newer version (X.Y.Z) is available. Please update using the same method you used to install." — with no link to the releases page, since update methods vary by installation type. Both implementations guard against network failures gracefully — errors are logged at debug level only and the UI remains unaffected.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[wheaney]

@copilot remove the codeql file (don't .gitignore it, just remove it from the commit) and also have the UIs just display a message, without a link to the releases page (since there are various ways to update depending on how they installed, but none of them require going to the releases page).

[Copilot]

@copilot remove the codeql file (don't .gitignore it, just remove it from the commit) and also have the UIs just display a message, without a link to the releases page (since there a...

Done in commit 1a729ac. The _codeql_detected_source_root symlink has been removed, and both UIs now show a plain message ("A newer version (X.Y.Z) is available. Please update using the same method you used to install.") with no link to the releases page.