fix(dispatcher): surface preg_match() engine failures instead of treating them as no-match

All dispatcher strategies checked preg_match() results with `!== 1`,
which conflates a genuine no-match (0) with a PCRE engine failure
(false), e.g. PREG_BACKTRACK_LIMIT_ERROR from a catastrophically
backtracking route pattern. Because dynamic routes for the same
method are combined into shared regex chunks, one such route could
make the preg_match() call for the whole chunk fail, silently
turning an unrelated, cheap route in that chunk into a spurious
NOT_FOUND.

Add a shared matchRoute() helper on RegexBasedAbstract that calls
preg_match() and throws a RuntimeException (including
preg_last_error_msg()) when it returns false, while preserving the
existing 0/1 no-match/match behavior. Update GroupCountBased,
GroupPosBased, CharCountBased and MarkBased to use it.

Fixes #167

src/Dispatcher/CharCountBased.php

@@ -7,7 +7,6 @@ use FastRoute\Dispatcher\Result\Matched;
 
 use function assert;
 use function end;
-use function preg_match;
 
 /** @final */
 class CharCountBased extends RegexBasedAbstract
@@ -18,7 +17,7 @@ class CharCountBased extends RegexBasedAbstract
         foreach ($routeData as $data) {
             assert(isset($data['suffix']));
 
-            if (preg_match($data['regex'], $uri . $data['suffix'], $matches) !== 1) {
+            if ($this->matchRoute($data['regex'], $uri . $data['suffix'], $matches) !== 1) {
                 continue;
             }