fix(rust): Flush stdout after print to fix stream mode display

When using --input <format>, the startup output showed [Stream mode: ]
(empty) instead of showing the format name like [Stream mode: SCC].

Root cause: The Rust logger's print() function uses print!() which
doesn't automatically flush stdout. When mixing C and Rust code that
both write to stdout, the Rust output was getting buffered and not
appearing before the C code continued writing.

The fix adds explicit std::io::stdout().flush() after each print!()
call to ensure output appears immediately and interleaves correctly
with C code.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: cfsmp3

src/rust/lib_ccxr/src/util/log.rs

@@ -281,8 +281,16 @@ impl<'a> CCExtractorLogger {
 
     fn print(&self, args: &Arguments<'a>) {
         match &self.target {
-            OutputTarget::Stdout => print!("{args}"),
-            OutputTarget::Stderr => eprint!("{args}"),
+            OutputTarget::Stdout => {
+                print!("{args}");
+                // Flush stdout to ensure output appears immediately, especially when
+                // mixing with C code that also writes to stdout
+                let _ = std::io::Write::flush(&mut std::io::stdout());
+            }
+            OutputTarget::Stderr => {
+                eprint!("{args}");
+                let _ = std::io::Write::flush(&mut std::io::stderr());
+            }
             OutputTarget::Quiet => {}
         }
     }