fix(workflow,skills): portable receipt report path; clippy type alias; warm rustfmt in test

- Workflow receipts rendered the report path with Path::display, so Windows
  emitted `.codewhale\reports\<id>.md`. written_run_report now returns a
  `/`-joined workspace-relative string on every platform (fixes the two
  windows-latest workflow receipt tests).
- parse_frontmatter's return type tripped clippy::type_complexity under
  -D warnings; name it with a `Frontmatter<'a>` alias.
- patch_normalizes_rust_in_an_already_clean_file warms the rustfmt proxy
  first: a cold Windows runner exceeded the 5s formatter budget on the first
  launch (5.23s), which skips normalization by design. Pre-existing flake,
  passes on other branches in 1.4-3.1s.

Local: cargo clippy -p codewhale-tui --all-targets --all-features with CI
flags clean; cargo test -p codewhale-tui --lib (workflow, apply_patch,
rust_format, skills filters) 415 passed, 0 failed; cargo fmt --check and
git diff --check clean; check-versions.sh --range-audit-advisory OK.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01R9rJEoMuUSRWznU6QjkE7h

crates/tui/src/skills/mod.rs

@@ -762,6 +762,9 @@ fn is_valid_skill_name(name: &str) -> bool {
             .all(|ch| ch.is_ascii_lowercase() || ch.is_ascii_digit() || ch == '-')
 }
 
+/// Parsed frontmatter: lowercased metadata keys and the body after the fence.
+pub(crate) type Frontmatter<'a> = (HashMap<String, String>, &'a str);
+
 /// Split a Markdown file into its `---` frontmatter metadata and body.
 ///
 /// Returns `Ok(None)` when the file does not open with a `---` fence. Keys are
@@ -770,7 +773,7 @@ fn is_valid_skill_name(name: &str) -> bool {
 /// one frontmatter reader: skills and Claude Code agent files both use it.
 pub(crate) fn parse_frontmatter(
     content: &str,
-) -> std::result::Result<Option<(HashMap<String, String>, &str)>, String> {
+) -> std::result::Result<Option<Frontmatter<'_>>, String> {
     if !content.trim_start().starts_with("---") {
         return Ok(None);
     }

crates/tui/src/tools/apply_patch.rs

@@ -1677,6 +1677,12 @@ mod tests {
     /// text, so the model's next patch context matches the bytes on disk.
     #[tokio::test]
     async fn patch_normalizes_rust_in_an_already_clean_file() {
+        // Warm the `rustfmt` proxy first: on a cold CI runner the first rustup
+        // shim launch alone can exceed the formatter's 5s budget, which skips
+        // normalization (by design) and fails this test for the wrong reason.
+        let _ = std::process::Command::new("rustfmt")
+            .arg("--version")
+            .output();
         let tmp = tempdir().expect("tempdir");
         let ctx = ToolContext::new(tmp.path().to_path_buf());
         let file = tmp.path().join("clean.rs");

crates/tui/src/tools/workflow/mod.rs

@@ -337,8 +337,7 @@ fn finish_workflow_controller(state: &WorkflowWorkspaceState, record: &WorkflowR
             "child_count": record.child_ids.len(),
             "detail": { "tool": "workflow", "action": "status", "run_id": truncate_chars(&record.run_id, 64) },
         });
-        let report = written_run_report(&controller.driver.workspace, &record.run_id)
-            .map(|path| path.display().to_string());
+        let report = written_run_report(&controller.driver.workspace, &record.run_id);
         if let Some(report) = &report {
             receipt["report"] = json!(report);
         }

crates/tui/src/tools/workflow/report.rs

@@ -52,10 +52,17 @@ fn run_report_relative_path(run_id: &str) -> Option<PathBuf> {
 }
 
 /// The run's report path relative to the workspace, only when the report
-/// was actually written.
-pub(super) fn written_run_report(workspace: &Path, run_id: &str) -> Option<PathBuf> {
+/// was actually written. Always `/`-separated: the path is shown to the model
+/// and the user in receipts, and must read the same on every platform.
+pub(super) fn written_run_report(workspace: &Path, run_id: &str) -> Option<String> {
     let relative = run_report_relative_path(run_id)?;
-    workspace.join(&relative).is_file().then_some(relative)
+    workspace.join(&relative).is_file().then(|| {
+        relative
+            .components()
+            .map(|part| part.as_os_str().to_string_lossy())
+            .collect::<Vec<_>>()
+            .join("/")
+    })
 }
 
 /// Bounded preview of a raw `responseSchema` reply for run records and