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.

tests/app/admin/components/MetricCard.test.tsx

@@ -0,0 +1,30 @@
+/**
+ * Component: Metric Card Tests
+ * Documentation: documentation/admin-dashboard.md
+ */
+
+// @vitest-environment jsdom
+
+import React from 'react';
+import { render, screen } from '@testing-library/react';
+import { describe, expect, it } from 'vitest';
+import { MetricCard } from '@/app/admin/components/MetricCard';
+
+describe('MetricCard', () => {
+  it('renders title, value, and subtitle with variant styles', () => {
+    const { container } = render(
+      <MetricCard
+        title="Errors"
+        value={3}
+        subtitle="Last 24h"
+        variant="error"
+        icon={<span>!</span>}
+      />
+    );
+
+    expect(screen.getByText('Errors')).toBeInTheDocument();
+    expect(screen.getByText('3')).toBeInTheDocument();
+    expect(screen.getByText('Last 24h')).toBeInTheDocument();
+    expect(container.firstChild).toHaveClass('bg-red-50');
+  });
+});