Add fit-to-size two-pass encoding, file argument, recipes, and batch mode

- Fit to size: computes H.264 bitrate from duration and runs a
  two-pass encode to land on a target size in MB
- lazyff FILE opens straight in the editor
- Recipes: save/load named edit stacks (~/.config/lazyff/recipes.json)
- Batch: mark files with Space, run one edit stack across all of them
  through a sequential job queue with per-file results

src/main.rs

@@ -1,6 +1,7 @@
 mod app;
 mod ffmpeg;
 mod ops;
+mod recipes;
 mod ui;
 
 use std::process::Command;
@@ -13,17 +14,27 @@ use ratatui::DefaultTerminal;
 use app::App;
 
 fn main() -> Result<()> {
+    let mut initial: Option<std::path::PathBuf> = None;
     if let Some(arg) = std::env::args().nth(1) {
         match arg.as_str() {
             "--version" | "-V" => {
                 println!("lazyff {}", env!("CARGO_PKG_VERSION"));
                 return Ok(());
             }
-            _ => {
+            "--help" | "-h" => {
                 println!("lazyff {} — a friendly TUI for FFmpeg", env!("CARGO_PKG_VERSION"));
-                println!("Usage: lazyff        (opens a file browser in the current directory)");
+                println!("Usage: lazyff [FILE]");
+                println!("  no argument   open a file browser in the current directory");
+                println!("  FILE          open this video/audio file straight in the editor");
                 return Ok(());
             }
+            _ => {
+                let path = std::path::PathBuf::from(&arg);
+                if !path.is_file() {
+                    bail!("{arg}: no such file");
+                }
+                initial = Some(path);
+            }
         }
     }
 
@@ -33,14 +44,17 @@ fn main() -> Result<()> {
         }
     }
 
+    // Probe the initial file before entering the alternate screen so errors
+    // print normally.
+    let app = App::new(initial)?;
+
     let mut terminal = ratatui::init();
-    let result = run(&mut terminal);
+    let result = run(&mut terminal, app);
     ratatui::restore();
     result
 }
 
-fn run(terminal: &mut DefaultTerminal) -> Result<()> {
-    let mut app = App::new()?;
+fn run(terminal: &mut DefaultTerminal, mut app: App) -> Result<()> {
     loop {
         app.poll_run_messages();
         terminal.draw(|f| ui::draw(f, &mut app))?;