refactor(lint): rewrite structural linters from Ruby to PHP

Fold scripts/lint and scripts/linters/*.rb into a standalone Composer
project under scripts/linters/, matching the scripts/plugin-class-classifier/
convention. Uses no external packages, only PHP + Composer autoloading.

Verified byte-for-byte identical output against the original Ruby
implementation, both on the current repo (all linters pass) and on a
synthetic fixture exercising every violation type.

Entry point moves from `scripts/lint` to `scripts/linters/lint`.

1 files changed, 48 insertions, 0 deletions

diff --git a/scripts/linters/src/Linters/NoFormatTrailingComma.php b/scripts/linters/src/Linters/NoFormatTrailingComma.php
new file mode 100644
index 00000000..dc364846
--- /dev/null
+++ b/scripts/linters/src/Linters/NoFormatTrailingComma.php
@@ -0,0 +1,48 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shirabe\Lint\Linters;
+
+use Shirabe\Lint\Linter;
+use Shirabe\Lint\Support\FileFinder;
+use Shirabe\Lint\Support\Paths;
+
+final class NoFormatTrailingComma implements Linter
+{
+    public function name(): string
+    {
+        return 'no_format_trailing_comma';
+    }
+
+    public function failureIntro(): string
+    {
+        return 'Found `,)` introduced by formatting. Remove it.';
+    }
+
+    public function check(string $rootDir, array $excludes): array
+    {
+        $errors = [];
+
+        foreach (FileFinder::rustFiles($rootDir) as $path) {
+            $relative = Paths::relativeTo($rootDir, $path);
+            if (in_array($relative, $excludes, true)) {
+                continue;
+            }
+
+            foreach (file($path) as $idx => $raw) {
+                if (!str_contains($raw, ',)')) {
+                    continue;
+                }
+                // `(,)` is a macro repetition fragment (e.g. `$(,)?`).
+                if (str_contains($raw, '(,)')) {
+                    continue;
+                }
+
+                $errors[] = "{$relative}:" . ($idx + 1) . ': trailing `,)` before a closing paren';
+            }
+        }
+
+        return $errors;
+    }
+}