v0.3.0: fix HTTP client leak, add tests and CI pipeline

Reuse a single long-poll HTTP client instead of creating one per
Events() call (~every 30s). Make TLS skip-verify configurable via
syncthing_insecure_tls. Log previously swallowed config errors.
Add unit tests for all monitor trackers, config, and state logic.
Add CI workflow (vet, golangci-lint, govulncheck, go test -race).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/monitor/conflicts_test.go

@@ -0,0 +1,28 @@
+package monitor
+
+import "testing"
+
+func TestConflictTracker_IncrementAndCount(t *testing.T) {
+	ct := NewConflictTracker()
+	if ct.Count() != 0 {
+		t.Fatalf("initial count should be 0, got %d", ct.Count())
+	}
+
+	ct.Increment()
+	ct.Increment()
+	ct.Increment()
+
+	if ct.Count() != 3 {
+		t.Errorf("expected 3, got %d", ct.Count())
+	}
+}
+
+func TestConflictTracker_SetCount(t *testing.T) {
+	ct := NewConflictTracker()
+	ct.Increment()
+	ct.SetCount(42)
+
+	if ct.Count() != 42 {
+		t.Errorf("expected 42 after SetCount, got %d", ct.Count())
+	}
+}