feat: change default profile from release to bench for build command

Change cargo codspeed build to default to --profile bench instead of --profile release to align with cargo bench behavior and allow users to leverage bench profile customizations.

Fixes COD-393

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

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

Author: art049

crates/cargo-codspeed/src/app.rs

@@ -66,7 +66,7 @@ enum Commands {
         jobs: Option<u32>,
 
         /// Build the benchmarks with the specified profile
-        #[arg(long, default_value = "release")]
+        #[arg(long, default_value = "bench")]
         profile: String,
     },
     /// Run the previously built benchmarks