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/application/use_cases/adjust_drift.rs

@@ -0,0 +1,85 @@
+use crate::domain::entities::Project;
+use crate::domain::value_objects::TrackId;
+use anyhow::{Result, anyhow};
+
+/// Ajusta o fator de escala temporal (drift) de uma faixa externa pelo TrackId.
+///
+/// Um `scale != 1.0` indica que o projeto precisará usar o pipeline mkvmerge.
+#[allow(dead_code)]
+pub struct AdjustDrift;
+
+impl AdjustDrift {
+    #[allow(dead_code)]
+    pub fn execute(project: &mut Project, id: TrackId, scale: f64) -> Result<()> {
+        if scale <= 0.0 {
+            return Err(anyhow!("O fator de escala deve ser maior que zero: {}", scale));
+        }
+        let track = project
+            .find_track_mut(id)
+            .ok_or_else(|| anyhow!("Faixa não encontrada: {:?}", id))?;
+        track.set_drift_scale(scale);
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::application::use_cases::add_audio_track::AddAudioTrack;
+    use crate::domain::entities::{MkvOutput, VideoFile};
+    use crate::domain::value_objects::{FilePath, SyncOffset, TrackLanguage};
+
+    fn make_project() -> Project {
+        Project::new(
+            VideoFile::new(FilePath::from("input.mkv")),
+            MkvOutput::new(FilePath::from("output.mkv")),
+        )
+        .unwrap()
+    }
+
+    #[test]
+    fn ajusta_drift_existente() {
+        let mut p = make_project();
+        let lang = TrackLanguage::new("por").unwrap();
+        AddAudioTrack::execute(
+            &mut p,
+            FilePath::from("audio.aac"),
+            SyncOffset::default(),
+            lang,
+            false,
+            String::new(),
+            1.0,
+        )
+        .unwrap();
+        let id = p.tracks[0].id();
+
+        AdjustDrift::execute(&mut p, id, 0.99983).unwrap();
+        assert!((p.tracks[0].drift_scale() - 0.99983).abs() < 1e-9);
+    }
+
+    #[test]
+    fn erro_se_id_inexistente() {
+        let mut p = make_project();
+        let result = AdjustDrift::execute(&mut p, TrackId::new(99), 0.99983);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn erro_se_scale_zero() {
+        let mut p = make_project();
+        let lang = TrackLanguage::new("por").unwrap();
+        AddAudioTrack::execute(
+            &mut p,
+            FilePath::from("audio.aac"),
+            SyncOffset::default(),
+            lang,
+            false,
+            String::new(),
+            1.0,
+        )
+        .unwrap();
+        let id = p.tracks[0].id();
+        let result = AdjustDrift::execute(&mut p, id, 0.0);
+        assert!(result.is_err());
+    }
+}