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, 124 insertions, 0 deletions

diff --git a/scripts/linters/src/Linters/ContiguousUseBlock.php b/scripts/linters/src/Linters/ContiguousUseBlock.php
new file mode 100644
index 00000000..c73ea6f8
--- /dev/null
+++ b/scripts/linters/src/Linters/ContiguousUseBlock.php
@@ -0,0 +1,124 @@
+<?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 ContiguousUseBlock implements Linter
+{
+    private const USE_START_RE = '/\A(?:pub(?:\([^)]*\))?\s+)?use\b/';
+
+    public function name(): string
+    {
+        return 'contiguous_use_block';
+    }
+
+    public function failureIntro(): string
+    {
+        return "Found blank lines splitting the leading `use` block into sections.\n"
+            . 'All `use` statements at the top of the file must be contiguous (no blank lines between them):';
+    }
+
+    public function check(string $rootDir, array $excludes): array
+    {
+        $errors = [];
+
+        foreach (FileFinder::rustFiles($rootDir) as $path) {
+            $relative = Paths::relativeTo($rootDir, $path);
+            if (in_array($relative, $excludes, true)) {
+                continue;
+            }
+
+            array_push($errors, ...$this->findSplitUseBlock($path, $relative));
+        }
+
+        return $errors;
+    }
+
+    /** @return list<string> */
+    private function findSplitUseBlock(string $path, string $relative): array
+    {
+        $lines = file($path);
+        $errors = [];
+        $count = count($lines);
+
+        $i = $this->skipPreamble($lines);
+        if ($i === null) {
+            return [];
+        }
+
+        while (true) {
+            $i = $this->consumeUseStatement($lines, $i);
+            if ($i >= $count) {
+                break;
+            }
+
+            $blanks = [];
+            $j = $i;
+            while ($j < $count) {
+                $stripped = trim($lines[$j]);
+                if ($stripped === '') {
+                    $blanks[] = $j;
+                    $j++;
+                } elseif (str_starts_with($stripped, '//') || str_starts_with($stripped, '#[')) {
+                    $j++;
+                } else {
+                    break;
+                }
+            }
+
+            if ($j < $count && preg_match(self::USE_START_RE, trim($lines[$j]))) {
+                foreach ($blanks as $bi) {
+                    $errors[] = "{$relative}:" . ($bi + 1) . ': blank line splits the leading `use` block';
+                }
+                $i = $j;
+            } else {
+                break;
+            }
+        }
+
+        return $errors;
+    }
+
+    /** @param list<string> $lines */
+    private function skipPreamble(array $lines): ?int
+    {
+        foreach ($lines as $idx => $raw) {
+            $stripped = trim($raw);
+            if (preg_match(self::USE_START_RE, $stripped)) {
+                return $idx;
+            }
+            if ($stripped === '' || str_starts_with($stripped, '//') || str_starts_with($stripped, '#![') || str_starts_with($stripped, '#[')) {
+                continue;
+            }
+
+            return null;
+        }
+
+        return null;
+    }
+
+    /** @param list<string> $lines */
+    private function consumeUseStatement(array $lines, int $startIdx): int
+    {
+        $braceDepth = 0;
+        $i = $startIdx;
+        $count = count($lines);
+
+        while ($i < $count) {
+            $line = $lines[$i];
+            $braceDepth += substr_count($line, '{') - substr_count($line, '}');
+            $done = $braceDepth <= 0 && str_ends_with(rtrim($line), ';');
+            $i++;
+            if ($done) {
+                return $i;
+            }
+        }
+
+        return $i;
+    }
+}