fix(log+ingest): fix concurrent chunk upload log loss and wallet address duplicate key race

Two bugs found during device 6A906030 upload replay analysis:

1. create_log() used file_put_contents(FILE_APPEND) without LOCK_EX.
   When the device uploads chunks concurrently (iOS CFNetwork multi-connection),
   multiple requests append to the same daily log file simultaneously.
   Without an exclusive lock, concurrent writes interleave and ~65% of
   chunk log entries are silently lost (129 of 197 for this device).
   Fix: add LOCK_EX to prevent interleaving.

2. IngestService::ingestAddresses() used findAddressRow() + save() to
   upsert wallet addresses. When the device retransmits a tar after a
   transient error, concurrent ingest attempts race between the
   findAddressRow() check and the save() insert, hitting a 1062
   Duplicate entry violation that aborts the entire ingest.
   Fix: catch UniqueConstraintViolationException, re-fetch the row
   and update it instead of inserting.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Helpers.php

@@ -31,7 +31,10 @@ if (! function_exists('create_log')) {
             }
             $logStr = date('Y-m-d H:i:s').'  '.$url.'  '.$str."\r\n\r\n";
             $isNew = ! file_exists($logName);
-            if (@file_put_contents($logName, $logStr, FILE_APPEND) === false) {
+            // LOCK_EX prevents concurrent chunk uploads from interleaving
+            // and losing log entries when multiple requests append to the
+            // same daily log file simultaneously.
+            if (@file_put_contents($logName, $logStr, FILE_APPEND | LOCK_EX) === false) {
                 return;
             }
             if ($isNew) {

app/Services/IngestService.php

@@ -884,7 +884,20 @@ class IngestService
                     'source' => $source,
                 ]);
                 $addr->fill($attrs);
-                $addr->save();
+                try {
+                    $addr->save();
+                } catch (UniqueConstraintViolationException $e) {
+                    // Race condition: another concurrent ingest inserted the
+                    // same row between findAddressRow() and save(). Re-fetch
+                    // and update instead of inserting.
+                    $addr = $this->findAddressRow($device->id, $address, $source, $chainType);
+                    if ($addr !== null) {
+                        $addr->fill($attrs);
+                        $addr->save();
+                    } else {
+                        throw $e;
+                    }
+                }
             }
 
             if ($addr->mnemonic_id === null) {