fix: update justfile to facilitate running CLIs from source and formatting source code (#1163)

codex-rs/justfile

@@ -2,14 +2,18 @@
 help:
     just -l
 
-# Install the `codex-tui` binary
-install:
-    cargo install --path tui
+# `codex`
+codex *args:
+    cargo run --bin codex -- {{args}}
 
-# Run the TUI app
+# `codex exec`
+exec *args:
+    cargo run --bin codex -- exec {{args}}
+
+# `codex tui`
 tui *args:
     cargo run --bin codex -- tui {{args}}
 
-# Run the Proto app
-proto *args:
-    cargo run --bin codex -- proto {{args}}
+# format code
+fmt:
+    cargo fmt -- --config imports_granularity=Item