feat: add AdjustExistingTrackDrift use case to adjust drift scale of existing tracks

- Implemented AdjustExistingTrackDrift struct with execute method to modify drift scale of existing tracks in a project.
- Added tests for adjusting drift scale, handling non-existent track IDs, and invalid scale values.
- Updated MediaTrackInfo and AudioTrack entities to include drift_scale field.
- Enhanced Project entity with needs_mkvmerge method to determine if mkvmerge is required based on drift scale.
- Integrated drift scale adjustments into existing track list UI, allowing users to modify drift values.
- Updated various use cases and UI components to support drift scale functionality, including add audio/subtitle forms and batch processing.
- Implemented mkvmerge availability check and integrated it into the application workflow for conditional processing.

src/ui/components/sync_offset_field.rs

@@ -3,9 +3,13 @@ use crate::domain::value_objects::SyncOffset;
 
 /// Campo de entrada para offset de sincronização em segundos (ex: "-1.2").
 /// Converte para SyncOffset(ms) internamente ao confirmar.
+/// Também suporta campo opcional de velocidade original (%) para correção de drift via mkvmerge.
 pub struct SyncOffsetField {
     pub raw: String,
     pub error: Option<String>,
+    /// Percentual de velocidade original (ex: "99.983" → scale 0.99983). Padrão: "100.00".
+    pub drift_raw: String,
+    drift_error: Option<String>,
 }
 
 impl SyncOffsetField {
@@ -14,10 +18,12 @@ impl SyncOffsetField {
         SyncOffsetField {
             raw: format!("{:.1}", seconds),
             error: None,
+            drift_raw: "100.00".to_string(),
+            drift_error: None,
         }
     }
 
-    /// Renderiza o campo e retorna true se o valor mudou.
+    /// Renderiza o campo de offset (sem o campo de drift).
     pub fn ui(&mut self, ui: &mut egui::Ui, label: &str) -> bool {
         let mut changed = false;
         ui.horizontal(|ui| {
@@ -35,6 +41,42 @@ impl SyncOffsetField {
         changed
     }
 
+    /// Renderiza offset + campo de velocidade original (drift) quando `mkvmerge_available`.
+    ///
+    /// - Quando `mkvmerge_available = false`: campo de velocidade é exibido desabilitado
+    ///   com tooltip pedindo instalação do MKVToolNix.
+    /// - Quando `scale ≠ 1.0`: exibe aviso discreto em laranja.
+    pub fn ui_with_drift(&mut self, ui: &mut egui::Ui, label: &str, mkvmerge_available: bool) -> bool {
+        let offset_changed = self.ui(ui, label);
+
+        ui.horizontal(|ui| {
+            ui.label("Velocidade original (%):");
+            let resp = ui.add_enabled(
+                mkvmerge_available,
+                egui::TextEdit::singleline(&mut self.drift_raw).desired_width(70.0),
+            );
+            if !mkvmerge_available {
+                resp.on_hover_text(
+                    "Instale MKVToolNix para usar correção de drift de velocidade.",
+                );
+            }
+            if let Ok(pct) = self.drift_raw.trim().parse::<f64>() {
+                if (pct - 100.0).abs() > 0.001 {
+                    ui.colored_label(
+                        egui::Color32::from_rgb(255, 160, 0),
+                        "⚠ requer mkvmerge",
+                    );
+                }
+            }
+        });
+
+        if let Some(ref err) = self.drift_error {
+            ui.colored_label(egui::Color32::RED, err);
+        }
+
+        offset_changed
+    }
+
     /// Tenta converter o valor atual para SyncOffset.
     pub fn parse(&mut self) -> Option<SyncOffset> {
         match SyncOffset::from_seconds_str(&self.raw) {
@@ -48,4 +90,26 @@ impl SyncOffsetField {
             }
         }
     }
+
+    /// Converte o percentual de velocidade para fator de escala (f64).
+    /// "100.00" → 1.0, "99.983" → 0.99983.
+    /// Retorna `1.0` em caso de erro (fallback seguro).
+    pub fn parse_drift(&mut self) -> f64 {
+        let trimmed = self.drift_raw.trim().trim_end_matches('%');
+        match trimmed.parse::<f64>() {
+            Ok(pct) if pct >= 1.0 && pct <= 999.99 => {
+                self.drift_error = None;
+                pct / 100.0
+            }
+            Ok(_) => {
+                self.drift_error =
+                    Some("Velocidade deve estar entre 1.0% e 999.99%".to_string());
+                1.0
+            }
+            Err(_) => {
+                self.drift_error = Some("Valor inválido".to_string());
+                1.0
+            }
+        }
+    }
 }