fix: prevent duplicate prompts and delayed output when pasting multi-command blocks

Blank lines and comments between pasted commands caused the loop to re-print
the prompt on each iteration. A prompt_needed flag ensures it fires once per
command, not once per skipped line.

Also flush stdout immediately after printing each result so output is not
held in the buffer until the next prompt flush.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: adityamukho

src/repl.rs

@@ -60,11 +60,14 @@ impl<'a> Repl<'a> {
 
         let mut command_buffer = String::new();
         let mut is_multiline = false;
+        // Only print the prompt once per command, not once per blank/comment line.
+        let mut prompt_needed = true;
 
         loop {
-            if interactive && !is_multiline {
+            if interactive && !is_multiline && prompt_needed {
                 print!("minigraf> ");
                 io::stdout().flush().ok();
+                prompt_needed = false;
             }
 
             let mut input = String::new();
@@ -106,8 +109,10 @@ impl<'a> Repl<'a> {
 
                         command_buffer.clear();
                         is_multiline = false;
+                        prompt_needed = true;
                         if interactive {
                             println!();
+                            io::stdout().flush().ok();
                         }
                     } else {
                         is_multiline = true;