fix(persist): use non-throwing directory_iterator increment in pruneDryRun

Replace range-based for over fs::directory_iterator with manual
it.increment(ec) form. Mid-iteration failures now break to a
best-effort partial list instead of throwing filesystem_error
across REAPER's C ABI. Split shared fec into reg_ec/sz_ec.

src/persist.cpp

@@ -281,18 +281,23 @@ PruneReport ReaSamplerSession::pruneDryRun() const {
     // and the manifest. Non-recursive: the bank folder is flat (capture writes files
     // directly here); skip any subdirectory. Size is stat'd here and cached by relative
     // path so the report's byte tally reuses the same on-disk read.
+    // Manual iterator form (it.increment(ec)) keeps the loop non-throwing: a mid-iteration
+    // failure (file removed, permission flip) breaks out with a best-effort partial list
+    // rather than propagating std::filesystem_error across REAPER's C ABI.
     std::vector<std::string> present;
     std::unordered_map<std::string, std::uint64_t> sizeByRel;
-    for (const auto& entry : fs::directory_iterator(bankDir, ec)) {
-        if (ec) break;
-        std::error_code fec;
-        if (!entry.is_regular_file(fec)) continue;  // skip subdirs / specials
+    fs::directory_iterator it(bankDir, ec);
+    for (; !ec && it != fs::directory_iterator{}; it.increment(ec)) {
+        const auto& entry = *it;
+        std::error_code reg_ec;
+        if (!entry.is_regular_file(reg_ec)) continue;  // skip subdirs / specials
         const std::string name = entry.path().filename().string();
         const std::string rel = bankRelativeForName(name);
         if (rel.empty()) continue;
         present.push_back(rel);
-        const std::uintmax_t sz = entry.file_size(fec);
-        sizeByRel[rel] = fec ? 0 : static_cast<std::uint64_t>(sz);
+        std::error_code sz_ec;
+        const std::uintmax_t sz = entry.file_size(sz_ec);
+        sizeByRel[rel] = sz_ec ? 0 : static_cast<std::uint64_t>(sz);
     }
 
     // The decision lives in the pure core — read-only inputs from the session's book and