tests: clean prepost artifacts in setup so verifyPath proves creation

project-prepost.test.ts checks that i-was-created.txt (extension) and
input-files.txt/output-files.txt (issue-10828) exist after render, but
only removed them in teardown. Those are fixed repo paths, so a run that
crashes between creating them and teardown leaves a stale copy — after
which a regression that stops the render creating them still passes
verifyPath. Add setup cleanup (matching the safeRemoveIfExists the file
already uses in teardown) so each verifyPath proves this render wrote the
file, not a leftover. Also clears i-exist.txt up front so pre-render's
"must not exist" guard starts clean after a prior crashed run.

Author: cderv

tests/smoke/project/project-prepost.test.ts

@@ -74,6 +74,13 @@ testQuartoCmd(
     }
   }],
   {
+    // remove artifacts a prior crashed run may have left behind, so verifyPath
+    // proves this render created i-was-created.txt (not a stale copy) and
+    // pre-render's i-exist.txt guard starts from a clean slate
+    setup: async () => {
+      safeRemoveIfExists(join(docs("project/prepost/extension"), "i-was-created.txt"));
+      safeRemoveIfExists(join(docs("project/prepost/extension"), "i-exist.txt"));
+    },
     teardown: async () => {
       safeRemoveIfExists(join(docs("project/prepost/extension"), "i-was-created.txt"));
       const siteDir = join(docs("project/prepost/extension"), "_site");
@@ -100,6 +107,12 @@ testQuartoCmd(
         "QUARTO_USE_FILE_FOR_PROJECT_INPUT_FILES": normalizePath(docs("project/prepost/issue-10828/input-files.txt")),
         "QUARTO_USE_FILE_FOR_PROJECT_OUTPUT_FILES": normalizePath(docs("project/prepost/issue-10828/output-files.txt"))
       },
+      // remove artifacts a prior crashed run may have left behind, so verifyPath
+      // proves this render wrote input-files.txt/output-files.txt, not a stale copy
+      setup: async () => {
+        safeRemoveIfExists(normalizePath(docs("project/prepost/issue-10828/input-files.txt")));
+        safeRemoveIfExists(normalizePath(docs("project/prepost/issue-10828/output-files.txt")));
+      },
       teardown: async () => {
         safeRemoveIfExists(normalizePath(docs("project/prepost/issue-10828/input-files.txt")));
         safeRemoveIfExists(normalizePath(docs("project/prepost/issue-10828/output-files.txt")));