PaintFE v1.4.15

PaintFE v1.4.15

This release includes the HEIC, AVIF and label-editing changes prepared for v1.4.14, plus fixes for the Windows release build and Linux CI.

• Open HEIC/HEIF images with built-in decoding, including corrected transparency.
• Install optional HEIC export and AVIF import/export packs in Preferences. Encoding stays offline after installation.
• Change interface wording with a searchable label editor for each language.
• Updated Document Info, added the supplied icons and matched Preferences headings to the other dialogs.
• Toolbar Save now saves to the current file. HEIC files keep their format and destination when the export pack is installed.
• Install PaintFE on Linux with DEB/RPM packages and signed package repositories. Arabic is also available.

HEIC and AVIF colour export is lossy 8-bit, even at quality 100. HEIC alpha is lossless. Use PFE to keep editable layers.

Windows codec checks were run locally. Linux/macOS codecs and Linux package installation still need platform testing. Arabic needs native-speaker review and does not yet have a full RTL layout.

Related to #196, #197 and #198. Issues remain open while users test and confirm.