Implement file hash-based library matching and remove fuzzy ASIN matching

Adds file hash-based matching for Audiobookshelf library items to ensure 100% accurate ASIN assignment for RMAB-organized content. Removes fuzzy matching from library availability checks, making all matching ASIN-only to eliminate false positives and race conditions. Updates database schema, processors, and matcher utilities; adds new tests and documentation for the new matching strategy. Removes obsolete scripts, Dockerfile, and related tests; updates docker-compose for test environments.

src/lib/utils/files-hash.ts

@@ -0,0 +1,74 @@
+/**
+ * File Hash Utility
+ * Documentation: documentation/fixes/file-hash-matching.md
+ *
+ * Generates deterministic hashes of audio file collections for accurate library matching.
+ * Used to match RMAB-organized audiobooks with Audiobookshelf library items.
+ */
+
+import crypto from 'crypto';
+import path from 'path';
+
+/**
+ * Supported audio file extensions for hash generation
+ */
+const AUDIO_EXTENSIONS = ['.m4b', '.m4a', '.mp3', '.mp4', '.aa', '.aax'];
+
+/**
+ * Generates a SHA256 hash of audio filenames for library matching.
+ *
+ * Process:
+ * 1. Extract basenames from file paths
+ * 2. Filter to supported audio extensions
+ * 3. Normalize to lowercase
+ * 4. Sort alphabetically
+ * 5. Generate SHA256 hash
+ *
+ * @param filePaths - Array of absolute or relative file paths
+ * @returns 64-character hex string (SHA256 hash) or empty string if no audio files
+ *
+ * @example
+ * ```typescript
+ * const hash = generateFilesHash([
+ *   '/path/to/Chapter 01.mp3',
+ *   '/path/to/Chapter 02.mp3',
+ *   '/path/to/cover.jpg'  // Filtered out (not audio)
+ * ]);
+ * // Returns: "abc123def456..." (64 chars)
+ * ```
+ */
+export function generateFilesHash(filePaths: string[]): string {
+  if (!filePaths || filePaths.length === 0) {
+    return '';
+  }
+
+  // Extract basenames and filter to audio files only
+  const audioBasenames = filePaths
+    .map((filePath) => path.basename(filePath))
+    .filter((basename) => {
+      const ext = path.extname(basename).toLowerCase();
+      return AUDIO_EXTENSIONS.includes(ext);
+    })
+    .map((basename) => basename.toLowerCase()) // Normalize case
+    .sort(); // Sort alphabetically for deterministic hash
+
+  // No audio files found
+  if (audioBasenames.length === 0) {
+    return '';
+  }
+
+  // Generate SHA256 hash
+  const hash = crypto
+    .createHash('sha256')
+    .update(JSON.stringify(audioBasenames))
+    .digest('hex');
+
+  return hash;
+}
+
+/**
+ * Validates if a hash string is a valid SHA256 hash
+ */
+export function isValidHash(hash: string): boolean {
+  return /^[a-f0-9]{64}$/i.test(hash);
+}