Implement comprehensive WebSocket subscription stability fixes

- Resolved critical issues causing subscriptions to drop after 30-60 seconds due to unconsumed receiver channels.
- Introduced per-subscription consumer goroutines to ensure continuous event delivery and prevent channel overflow.
- Enhanced REQ parsing to handle both wrapped and unwrapped filter arrays, eliminating EOF errors.
- Updated publisher logic to correctly send events to receiver channels, ensuring proper event delivery to subscribers.
- Added extensive documentation and testing tools to verify subscription stability and performance.
- Bumped version to v0.26.2 to reflect these significant improvements.

scripts/test-subscriptions.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+# Simple subscription stability test script
+
+set -e
+
+RELAY_URL="${RELAY_URL:-ws://localhost:3334}"
+DURATION="${DURATION:-60}"
+KIND="${KIND:-1}"
+
+echo "==================================="
+echo "Subscription Stability Test"
+echo "==================================="
+echo ""
+echo "This tool tests whether subscriptions remain stable over time."
+echo ""
+echo "Configuration:"
+echo "  Relay URL: $RELAY_URL"
+echo "  Duration: ${DURATION}s"
+echo "  Event kind: $KIND"
+echo ""
+echo "To test properly, you should:"
+echo "  1. Start this test"
+echo "  2. In another terminal, publish events to the relay"
+echo "  3. Verify events are received throughout the test duration"
+echo ""
+
+# Check if the test tool is built
+if [ ! -f "./subscription-test" ]; then
+    echo "Building subscription-test tool..."
+    go build -o subscription-test ./cmd/subscription-test
+    echo "✓ Built"
+    echo ""
+fi
+
+# Run the test
+echo "Starting test..."
+echo ""
+
+./subscription-test -url "$RELAY_URL" -duration "$DURATION" -kind "$KIND" -v
+
+exit $?