Replace deleted_files with manifest-based updater cleanup, add release workflow

- Add manifest.json generation script (scripts/generate-manifest.php)
- Add Updater::cleanStaleFiles() that removes files not in manifest
- Add /api/v1/update/clean endpoint with backward compatibility
- Add configurable update_protected_paths in config/invoiceshelf.php
- Update frontend to use clean step instead of delete step
- Add GitHub Actions release workflow triggered on version tags
- Add .github/release.yml for auto-generated changelog categories
- Update Makefile to include manifest generation and scripts directory

scripts/generate-manifest.php

@@ -0,0 +1,61 @@
+<?php
+
+/**
+ * Generate manifest.json for the InvoiceShelf updater.
+ *
+ * Usage: php scripts/generate-manifest.php [base-directory]
+ *
+ * Outputs a sorted JSON array of all relative file paths in the given
+ * directory. The manifest is written to {base-directory}/manifest.json
+ * and is used by the updater to detect and remove stale files after
+ * copying a new release.
+ */
+$basePath = rtrim($argv[1] ?? '.', '/');
+
+if (! is_dir($basePath)) {
+    fwrite(STDERR, "Error: '{$basePath}' is not a directory.\n");
+    exit(1);
+}
+
+$excludedPrefixes = [
+    '.env',
+    '.git/',
+    'storage/',
+    'vendor/',
+    'node_modules/',
+    'Modules/',
+    'bootstrap/cache/',
+    'public/storage/',
+];
+
+$files = [];
+
+$iterator = new RecursiveIteratorIterator(
+    new RecursiveDirectoryIterator($basePath, RecursiveDirectoryIterator::SKIP_DOTS),
+    RecursiveIteratorIterator::SELF_FIRST
+);
+
+foreach ($iterator as $file) {
+    if (! $file->isFile()) {
+        continue;
+    }
+
+    $relativePath = substr($file->getPathname(), strlen($basePath) + 1);
+
+    foreach ($excludedPrefixes as $prefix) {
+        if (str_starts_with($relativePath, $prefix)) {
+            continue 2;
+        }
+    }
+
+    $files[] = $relativePath;
+}
+
+sort($files);
+
+$json = json_encode($files, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
+
+file_put_contents($basePath.'/manifest.json', $json."\n");
+
+$count = count($files);
+fwrite(STDOUT, "manifest.json written with {$count} files.\n");