fix: guard Tia argv scanning against non-string args (#1736)

The Tia plugin scans the raw argv with str_starts_with() in
argumentPresent() and hasExplicitPathArgument(). In the parallel worker
path (bin/worker.php) the unserialized argv can contain an integer
--random-order-seed value as a separate element, which made
str_starts_with() throw:

    TypeError: str_starts_with(): Argument #1 ($haystack) must be of
    type string, int given

This is the same class of bug as #1206, which was only fixed in
HandleArguments; it resurfaced in the newer Tia plugin. Cast each argv
element to string before scanning, mirroring the #1206 fix.

Adds a regression test, and updates the parallel count assertion and the
success snapshot to account for it.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/.snapshots/success.txt

@@ -1752,6 +1752,10 @@
   ✓ output format → it returns a 32-character hex xxh128 hash
   ✓ output format → it returns a stable hash for empty content
 
+   PASS  Tests\Unit\Plugins\Tia\IsEnabledForRun
+  ✓ does not throw when an integer --random-order-seed is passed as a separate argv element
+  ✓ still detects --tia when an integer argument is present
+
    PASS  Tests\Unit\Preset
   ✓ preset invalid name
   ✓ preset → myFramework
@@ -1937,4 +1941,4 @@
   ✓ pass with dataset with ('my-datas-set-value')
   ✓ within describe → pass with dataset with ('my-datas-set-value')
 
-  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1328 passed (3008 assertions)
+  Tests:    2 deprecated, 4 warnings, 5 incomplete, 2 notices, 40 todos, 35 skipped, 1330 passed (3010 assertions)