Refactor compression lifecycle, consolidate messages, and add no-upda…

[CodeDead]

…te window

• Add compressrNoUpdate language key across all locales (10 languages) and wire it into the new NoUpdate window view
• Replace all Ignore* enum variants with a single Message::Noop variant
• Remove current_scale field from Window struct; scale_factor now always returns 1.0
• Remove compression_succeeded field from State — completion is now inferred from the results vector
• Add compression_aborted: Arc<AtomicBool> to State; set on main window close during compression to cancel in-flight tasks
• Add cancellation checks throughout compress_single so running operations abort promptly when the window is closed
• Validate output path is an existing directory before starting compression (fail early instead of late)
• Change CompressionParams.output_path to Arc<str> to share across batch items
• Return &'static str from get_platform() instead of an owned String
• Remove Serialize derives from Version/Platform (only deserialized)
• Replace exhaustive theme match with dynamic Theme::ALL lookup
• Add pixel_data() helper and use native color types in BMP/TIFF encoders
• Minor cleanup: use first() over [0], format! over .to_string() +, inline trivial variables, fold for totals