refactor(extract): report extraction progress through the sink

The extraction spinner drew straight to stderr from inside the
library, so every consumer got terminal UI it never asked for.
extract_tarball and its helpers now count extracted files themselves
and emit Progress events; rendering belongs to the caller.

crates/ecr-cli/src/main.rs

@@ -38,7 +38,7 @@ fn main() -> Result<()> {
         arch: args.arch.clone().unwrap_or_default(),
         no_cache: args.no_cache,
     };
-    let rootfs = cache.prepare(&request)?;
+    let rootfs = cache.prepare(&request, &ecr::NoProgress)?;
 
     // Branch based on --kernel flag
     // Option<Option<PathBuf>> (require_equals: the value must use =PATH syntax