Keep ESP contact saves responsive on PSRAM boards

Extend the cooperative contact transaction to uncached ESP32 storage,
including the PSRAM policy used by the XIAO and V4. Preserve owned contact
copies, the 152-byte disk format, revision cancellation and synchronous
durability operations. Keep contact capacities unchanged.

Avoid SDK error logs when optional blob or transaction cleanup files are
absent, while preserving metadata and deletion failure handling.

Validate cached ESP/nRF and uncached PSRAM paths under ASan/UBSan,
including bounded writes, mutation cancellation, faults, recovery and
reboot readback. Update the existing uncached production fixture.

src/helpers/ContactFileTransaction.h

@@ -34,6 +34,11 @@ private:
     present = fs->exists(path);
     return true;
   }
+  static bool removeIfPresent(FILESYSTEM* fs, const char* path,
+                              PresenceProbe presence) {
+    bool present = false;
+    return probe(fs, path, present, presence) && (!present || fs->remove(path));
+  }
 public:
   enum class CommitProgress : uint8_t { Pending, Succeeded, Failed };
   static bool recover(FILESYSTEM* fs, const char* target,
@@ -52,7 +57,7 @@ public:
     snprintf(_temp, sizeof(_temp), "%s.tmp", target);
     snprintf(_backup, sizeof(_backup), "%s.bak", target);
     if (!recover(fs, target, presence)) return;
-    if (fs->exists(_temp) && !fs->remove(_temp)) return;
+    if (!removeIfPresent(fs, _temp, presence)) return;
 #if defined(RP2040_PLATFORM)
     _file = fs->open(_temp, "w");
 #else
@@ -63,7 +68,7 @@ public:
   ~ContactFileTransaction() {
     if (_file) _file.close();
     if (_verify) _verify.close();
-    if (!_finished) _fs->remove(_temp);
+    if (!_finished) removeIfPresent(_fs, _temp, _presence);
   }
   operator bool() const { return _ok; }
   bool readyToPublish() const {
@@ -132,8 +137,10 @@ public:
     }
     if (ok) ok = _fs->rename(_temp, _target);
     if (!ok && backed_up) _fs->rename(_backup, _target);
-    if (ok) _fs->remove(_backup);
-    else _fs->remove(_temp);
+    // Cleanup remains best effort after the publish/rollback result, but an
+    // absent file must not trigger the SDK's error log on the shared USB port.
+    if (ok) removeIfPresent(_fs, _backup, _presence);
+    else removeIfPresent(_fs, _temp, _presence);
     _finished = true;
     return ok ? CommitProgress::Succeeded : CommitProgress::Failed;
   }