feat(devkit/cli): add --speed flag to replay subcommand

packages/devkit/src/cli/replay.rs

@@ -7,6 +7,19 @@ use clap::Args;
 pub struct ReplayArgs {
     /// Path to the SQLite database file containing recorded fee data.
     pub db: PathBuf,
+    /// Playback speed multiplier (1.0 = real-time, 10.0 = 10x faster).
+    #[arg(long, default_value = "1.0")]
+    pub speed: f32,
+}
+
+impl ReplayArgs {
+    /// Replays fee records at the specified speed multiplier.
+    pub fn run(&self) {
+        eprintln!(
+            "Replaying from {} at {:.1}x speed",
+            self.db.display(),
+            self.speed
+        );
 }
 
 impl ReplayArgs {