Clean workspace (make it match the depot)

- Actions -> Clean workspace: preview extra/deleted/modified files, then apply
  p4 clean (opened files untouched)
- Backend p4 clean -n / clean

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src-tauri/src/lib.rs

@@ -1867,6 +1867,31 @@ async fn p4_latest_change(state: State<'_, AppState>, scope: String) -> Result<V
     Ok(v.into_iter().next().unwrap_or(Value::Null))
 }
 
+/// Preview `p4 clean` — files that would be deleted (local extras), restored
+/// (locally deleted) or refreshed (locally modified but not opened) to make the
+/// workspace exactly match the depot. Non-destructive (`-n`).
+#[tauri::command]
+async fn p4_clean_preview(state: State<'_, AppState>, scope: String) -> Result<Vec<Value>, String> {
+    let conn = current(&state)?;
+    run_json(&conn, &["clean", "-n", &scope_spec(&scope)]).or_else(|e| {
+        let l = e.to_lowercase();
+        if l.contains("no file") || l.contains("up-to-date") || l.contains("no such") || l.contains("no differing") {
+            Ok(Vec::new())
+        } else {
+            Err(e)
+        }
+    })
+}
+
+/// Apply `p4 clean`: make the workspace match the depot, discarding un-opened
+/// local edits/adds/deletes. Streams progress.
+#[tauri::command]
+async fn p4_clean_apply(state: State<'_, AppState>, scope: String) -> Result<String, String> {
+    let conn = current(&state)?;
+    let msg = run_stream(&conn, &["clean", &scope_spec(&scope)], "sync")?;
+    Ok(if msg.is_empty() { "Workspace already matches the depot.".into() } else { msg })
+}
+
 /// Full revision history of a single file (`p4 filelog -l`), including
 /// per-revision changelist, action, user, time and description. Returns the
 /// tagged object with rev0/change0/action0/… arrays.
@@ -2223,6 +2248,8 @@ pub fn run() {
             p4_switch_stream,
             p4_stream_integ,
             p4_filelog,
+            p4_clean_preview,
+            p4_clean_apply,
             p4_jobs,
             p4_fix,
             p4_job_spec,