testkit: run the meshing skill on the corpus and samples (cargo xtask skill-results)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

crates/testkit/src/bin/skill.rs

@@ -0,0 +1,37 @@
+//! `skill [--part NAME] [--no-write] --work DIR`: see [`fieldcraft_testkit::skill`]; run it as
+//! `cargo xtask skill-results`, which also draws the section pictures.
+#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
+#![forbid(unsafe_code)]
+
+use std::path::Path;
+use std::process::ExitCode;
+
+const USAGE: &str = "usage: skill --work DIR [--part NAME] [--no-write]";
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let (mut only, mut work, mut write) = (None, None, true);
+    let mut it = args.iter();
+    while let Some(a) = it.next() {
+        match a.as_str() {
+            "--part" => only = it.next().map(String::as_str),
+            "--work" => work = it.next().map(String::as_str),
+            "--no-write" => write = false,
+            other => {
+                eprintln!("error: unknown argument `{other}`\n{USAGE}");
+                return ExitCode::FAILURE;
+            }
+        }
+    }
+    let Some(work) = work else {
+        eprintln!("error: --work is needed\n{USAGE}");
+        return ExitCode::FAILURE;
+    };
+    match fieldcraft_testkit::skill::run(&fieldcraft_testkit::corpus::workspace_root(), Path::new(work), only, write) {
+        Ok(()) => ExitCode::SUCCESS,
+        Err(e) => {
+            eprintln!("error: {e}");
+            ExitCode::FAILURE
+        }
+    }
+}