feat: slide images moved to slides/img/, direct path in TOML, slides_test binary

- Moved 16 slide PNGs from assets/ to slides/img/
- Replaced [icons] mapping section with direct paths in icon field
- Added slides_test standalone binary for testing slideshows
- Added default-run = "yali-rs" in Cargo.toml to fix cargo run ambiguity
- Fixed edit dialog auto-resize and text field wrapping in partition.rs
- Updated branding.rs to load external slides from slides/ directory
- Removed [slides] section from branding.toml files
- Revamped CopyFilesJob with find-based progress tracking (rsync --out-format)
- Fixed install progress bar visibility logic
- Tweaked auto-install CLI output with sub-progress and current file
- Switched language-icon.svg to white fills for dark theme
- Minor locale fixes

locales/en.toml

@@ -98,7 +98,7 @@ finish_title = "Installation Complete"
 # ── Execution (extra) ─────────────────────────────────────
 install_failed  = "Installation failed"
 install_done    = "Installation complete! Click Next to continue."
-install_current_file = "Current file"
+install_current_file = "Copy file"
 retry_install   = "Retry"
 finish_next     = "Finish →"
 

locales/tr.toml

@@ -97,7 +97,7 @@ finish_title = "Kurulum Tamamlandı"
 # ── Execution (ek) ────────────────────────────────────────
 install_failed  = "Kurulum başarısız"
 install_done    = "Kurulum tamamlandı! Devam etmek için İleri'ye basın."
-install_current_file = "İşlemdeki dosya"
+install_current_file = "Kopyalanan dosya"
 retry_install   = "Yeniden Dene"
 finish_next     = "Tamamlandı →"