Refactor lock-ops to encapsulate global state in RelayHealthManager class

- Replaces module-level mutable state (`metricsByRelay`, `lastSnapshotAt`) with `RelayHealthManager` class.
- Moves state-dependent functions (`ensureRelayMetrics`, `rankRelaysByHealth`, etc.) to class methods.
- Updates `queryLocks` and `publishLock` to support dependency injection for `healthManager`.
- Maintains backward compatibility via `defaultHealthManager` singleton.
- Adds `test/relay-health-manager.test.mjs` to verify state isolation and functionality.

Co-authored-by: PR0M3TH3AN <[email protected]>

test/relay-health-manager.test.mjs

@@ -0,0 +1,72 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert';
+import { RelayHealthManager } from '../src/lock-ops.mjs';
+
+describe('RelayHealthManager', () => {
+  it('should isolate state between instances', () => {
+    const manager1 = new RelayHealthManager();
+    const manager2 = new RelayHealthManager();
+
+    const config = {
+      rollingWindowSize: 5,
+      failureThreshold: 3,
+      quarantineCooldownMs: 1000,
+      maxQuarantineCooldownMs: 5000,
+    };
+
+    manager1.recordOutcome('wss://relay1', true, null, 100, config);
+
+    // Manager 1 should have metrics
+    const metrics1 = manager1.ensureMetrics('wss://relay1', config);
+    assert.strictEqual(metrics1.recentOutcomes.length, 1);
+
+    // Manager 2 should have empty metrics for relay1
+    const metrics2 = manager2.ensureMetrics('wss://relay1', config);
+    assert.strictEqual(metrics2.recentOutcomes.length, 0);
+  });
+
+  it('should prioritize relays based on health', () => {
+    const manager = new RelayHealthManager();
+    const config = {
+      rollingWindowSize: 5,
+      failureThreshold: 2,
+      quarantineCooldownMs: 1000,
+      maxQuarantineCooldownMs: 5000,
+      minActiveRelayPool: 1,
+    };
+
+    // Relay 1: Healthy
+    manager.recordOutcome('wss://healthy', true, null, 100, config);
+
+    // Relay 2: Failing
+    manager.recordOutcome('wss://failing', false, 'error', 100, config);
+    manager.recordOutcome('wss://failing', false, 'error', 100, config); // Quarantined
+
+    const result = manager.prioritizeRelays(['wss://healthy', 'wss://failing'], config);
+
+    assert.deepStrictEqual(result.prioritized, ['wss://healthy']);
+
+    // Check ranking
+    const healthyRank = result.ranked.find(r => r.relay === 'wss://healthy');
+    const failingRank = result.ranked.find(r => r.relay === 'wss://failing');
+
+    assert.ok(healthyRank.score > failingRank.score);
+    assert.strictEqual(failingRank.summary.quarantined, true);
+  });
+
+  it('should reset state correctly', () => {
+    const manager = new RelayHealthManager();
+    const config = {
+        rollingWindowSize: 5,
+        failureThreshold: 3,
+        quarantineCooldownMs: 1000,
+        maxQuarantineCooldownMs: 5000,
+    };
+
+    manager.recordOutcome('wss://relay1', true, null, 100, config);
+    assert.strictEqual(manager.metricsByRelay.size, 1);
+
+    manager.reset();
+    assert.strictEqual(manager.metricsByRelay.size, 0);
+  });
+});