Merge main into fix/1743-render-overwrite-confirm

output_guard joins the split engine lib.rs; the overwrite tests move to tests/render_overwrite.rs
(#2491) and the regression workflow's test filter follows.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RDvxCS8xcR28VArjzn1x7U

apps/effectcraft-cli/tests/it/cli.rs

@@ -7,7 +7,7 @@ use std::process::{Command, Stdio};
 use serde_json::{Value, json};
 
 fn bin() -> Command {
-    Command::new(env!("CARGO_BIN_EXE_effectcraft-cli"))
+    Command::new(crate::binary())
 }
 
 /// Run with `--json`; returns (exit code, parsed stdout).