[rootsiemen]

Closes #1189

The reset-failure branch in SymfonyController::resetServices() logged only the exception message plus file/line, so PSR-3 loggers (e.g. Monolog) dropped the stack trace. It now logs the Throwable itself under the 'exception' context key, matching the sibling services_resetter resolution failure in the same class; the manual file/line keys are removed since the formatter derives them from the Throwable.

Test evidence:

• tests/SymfonyControllerTest.php::testServicesResetterFailureIsLoggedAndDoesNotBreakNextRequest now asserts the logged context carries the same Throwable instance and no manual file/line keys, still over two requests (both 200, resetter runs once per request). The updated test failed on the old code (logged the message string) and passes after the fix.
• tests/SymfonyControllerTest.php: 35 tests, 124 assertions, OK.
• Full suite: 2914 tests, 9 pre-existing failures (composer-audit E2E + root-readable-file tests, all failing identically on pristine master), 44 skipped.
• PHPStan level 8 and php-cs-fixer clean on the touched files; bin/check-changelog.php OK. Full bin/lint.sh fails only on pre-existing shellcheck/hadolint environment issues (hadolint not installed; SC2015 in untouched bin/worktree-done.sh).