ltc: rename DensePPLNSRing -> DensePPLNSWindow (SAFE-COSMETIC)

The class is a std::deque sliding window, not a ring buffer; the name
was a misnomer. Pure symbol+comment rename, zero behavior change.
The actual ring buffer is the V37 work on v37-dev.

Author: frstrtr

src/impl/ltc/node.cpp

@@ -12,10 +12,10 @@
 #include <iomanip>
 #include <random>
 
-// Static members for DensePPLNSRing precomputed decay table
-std::vector<uint64_t> ltc::DensePPLNSRing::s_decay_table;
-uint64_t ltc::DensePPLNSRing::s_decay_per = 0;
-bool ltc::DensePPLNSRing::s_table_initialized = false;
+// Static members for DensePPLNSWindow precomputed decay table
+std::vector<uint64_t> ltc::DensePPLNSWindow::s_decay_table;
+uint64_t ltc::DensePPLNSWindow::s_decay_per = 0;
+bool ltc::DensePPLNSWindow::s_table_initialized = false;
 
 // Helper: read current RSS from /proc/self/status (Linux only)
 static long get_rss_mb() {

src/impl/ltc/share_tracker.hpp

@@ -145,7 +145,7 @@ struct PPLNSEntry {
     std::vector<unsigned char> script;      // payout script (variable-length)
 };
 
-class DensePPLNSRing {
+class DensePPLNSWindow {
 public:
     static constexpr uint64_t DECAY_PRECISION = 40;
     static constexpr uint64_t DECAY_SCALE = uint64_t(1) << DECAY_PRECISION;
@@ -244,15 +244,15 @@ class DensePPLNSRing {
 };
 
 // ── Head-Level Incremental PPLNS ─────────────────────────────────────────
-// Maintains a DensePPLNSRing + cached CumulativeWeights per active head.
+// Maintains a DensePPLNSWindow + cached CumulativeWeights per active head.
 // When verifying consecutive shares along a chain:
 //   1. rebuild() at first share's parent: O(chain_len) — one hash map walk
 //   2. extend() for each subsequent share: O(1) ring push + O(chain_len) dense recompute
 // Total for N shares: O(chain_len + N × chain_len) sequential ops
 // vs current: O(N × chain_len) random hash map ops — ~10x faster per op.
 
 class HeadPPLNS {
-    DensePPLNSRing m_ring;
+    DensePPLNSWindow m_ring;
     CumulativeWeights m_cached;
     bool m_dirty{true};
 
@@ -306,7 +306,7 @@ class HeadPPLNS {
 
     bool valid() const { return !m_ring.empty(); }
     int32_t window_size() const { return m_ring.size(); }
-    const DensePPLNSRing& ring() const { return m_ring; }
+    const DensePPLNSWindow& ring() const { return m_ring; }
 };
 
 // --- ShareTracker ---