BLE P2P stability: PSRAM zero-init, pool sizing, stuck-state recovery

Root cause: Bytes objects stored in PSRAM-allocated BLEInterface had
corrupted shared_ptr members from uninitialized memory, causing crashes
in processDiscoveredPeers(). Fixed by using heap_caps_calloc instead of
heap_caps_malloc for PSRAM placement-new allocation.

Additional fixes:
- Reduce pool sizes to fit memory budget (reassembler 134KB→17KB,
  fragmenters 8→4, handshakes 32→4, pending data 64→8)
- Store local MAC as BLEAddress struct instead of Bytes to avoid
  heap allocation in PSRAM-resident object
- Move setLocalMac after platform start (NimBLE needs to be running
  for valid random address), add lazy MAC init fallback in loop()
- Add stuck-state detector: resets GAP state machine if hardware
  is idle but state machine thinks it's busy
- Enhance getLocalAddress with 3 fallback methods (NimBLE API,
  ble_hs_id_copy_addr RANDOM, esp_read_mac efuse)
- Fix C++17 structured binding to C++11 compatibility
- Increase BLE task stack 8KB→12KB for string ops in debug logs

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

lib/ble_interface/BLEPeerManager.cpp

@@ -14,7 +14,7 @@
 namespace RNS { namespace BLE {
 
 BLEPeerManager::BLEPeerManager() {
-    _local_mac = Bytes(6);  // Initialize to zeros
+    memset(_local_mac_addr.addr, 0, 6);  // Initialize to zeros
 
     // Initialize all pools to empty state
     for (size_t i = 0; i < PEERS_POOL_SIZE; i++) {
@@ -31,7 +31,8 @@ BLEPeerManager::BLEPeerManager() {
 
 void BLEPeerManager::setLocalMac(const Bytes& mac) {
     if (mac.size() >= Limits::MAC_SIZE) {
-        _local_mac = Bytes(mac.data(), Limits::MAC_SIZE);
+        memcpy(_local_mac_addr.addr, mac.data(), Limits::MAC_SIZE);
+        DEBUG("BLEPeerManager: Local MAC set to " + _local_mac_addr.toString());
     }
 }
 
@@ -321,7 +322,8 @@ PeerInfo* BLEPeerManager::getBestConnectionCandidate() {
 }
 
 bool BLEPeerManager::shouldInitiateConnection(const Bytes& peer_mac) const {
-    return shouldInitiateConnection(_local_mac, peer_mac);
+    Bytes our_mac(_local_mac_addr.addr, Limits::MAC_SIZE);
+    return shouldInitiateConnection(our_mac, peer_mac);
 }
 
 bool BLEPeerManager::shouldInitiateConnection(const Bytes& our_mac, const Bytes& peer_mac) {