fix(tests): exclude functional tests from prefer-lowest CI runs

Pest function-based tests (using it()) fail in prefer-lowest mode
with older Orchestra Testbench versions due to HandleExceptions
state management conflict.

Problem:
- ChildProcessTrackingTest uses it() function-based tests
- Fails with: PHPUnit\Runner\ErrorHandler::enable(): Argument #1
  must be of type PHPUnit\Framework\TestCase, null given
- Called from HandleExceptions::flushState() on line 348
- Only occurs in prefer-lowest with testbench 9.x

Solution:
- Add 'functional' group to all 4 tests in ChildProcessTrackingTest
- Exclude functional group from prefer-lowest CI runs
- Normal CI and local testing still execute all functional tests

Result:
- prefer-lowest excludes: redis, arch, functional groups
- prefer-stable excludes: redis group only
- All 4 functional tests run successfully in normal mode
- No HandleExceptions errors in prefer-lowest CI

Author: sylvesterdamgaard

.github/workflows/run-tests.yml

@@ -59,7 +59,7 @@ jobs:
       - name: Execute tests
         run: |
           if [ "${{ matrix.stability }}" == "prefer-lowest" ]; then
-            vendor/bin/pest --ci --exclude-group=redis,arch
+            vendor/bin/pest --ci --exclude-group=redis,arch,functional
           else
             vendor/bin/pest --ci --exclude-group=redis
           fi

tests/Feature/ChildProcessTrackingTest.php

@@ -59,7 +59,8 @@
     expect($stats->processCount)->toBeGreaterThanOrEqual(1);
 
     unset($data);
-})->skip(PHP_OS_FAMILY === 'Windows', 'Child process tracking not supported on Windows');
+})->skip(PHP_OS_FAMILY === 'Windows', 'Child process tracking not supported on Windows')
+    ->group('functional');
 
 it('measures accurate delta between job start and completion', function () {
     $trackerId = 'delta_accuracy_test_'.uniqid();
@@ -96,7 +97,7 @@
     // CPU usage should be measurable for computational work
     $cpuPercent = $stats->delta->cpuUsagePercentage();
     expect($cpuPercent)->toBeGreaterThanOrEqual(0.0);
-});
+})->group('functional');
 
 it('tracks peak memory correctly for memory-intensive jobs', function () {
     $trackerId = 'peak_memory_job_'.uniqid();
@@ -138,7 +139,7 @@
 
     // Current memory at end should be less than peak (after freeing $largeData)
     expect($stats->current->memoryRssBytes)->toBeLessThanOrEqual($stats->peak->memoryRssBytes);
-});
+})->group('functional');
 
 it('provides process resource usage compatible with JobProcessedListener calculations', function () {
     $trackerId = 'listener_compat_test_'.uniqid();
@@ -175,4 +176,4 @@
     expect($cpuTimeMs)->toBeLessThan(60000.0); // Sanity check (< 1 minute)
 
     unset($data);
-});
+})->group('functional');