handshake-capture-c6: production SD gating (SD_IsReady), v1.0.1

- Gate capture on SD_IsReady() after successful SD_Init; avoid false
  'insert SD' when SD.cardType() lies after WiFi on shared SPI with LCD
- SD_Init: LCD CS high, SD.end() on empty card; HandshakeCapture save path
  retries SD_Init before discard
- FAT filename sanitize, discard deadlocks, WPA3 scan labels, docs (README,
  PRODUCTION, IMPROVEMENTS), firmware version 1.0.1

Made-with: Cursor

handshake-capture-c6/HandshakeCapture.h

@@ -5,7 +5,14 @@
 #include "esp_wifi.h"
 #include <SD.h>
 
-#define MAX_SLOTS 3
+/** Semantic version (Serial banner + support). */
+#define HANDSHAKE_FIRMWARE_VERSION "1.0.1"
+
+/** SD write only after this many EAPOL-Key frames (full WPA/WPA2 4-way). */
+#define HANDSHAKE_EAPOL_FRAMES 4
+
+// Two APs at once: less on-air contention, more time per target before rotating.
+#define MAX_SLOTS 2
 #define MAX_NETWORKS 20
 #define MAX_CLIENTS_PER_SLOT 8
 #define PCAP_MAX_SIZE 4096
@@ -63,7 +70,7 @@ enum CapturePhase : uint8_t {
 extern WifiNetwork networks[MAX_NETWORKS];
 extern CaptureSlot slots[MAX_SLOTS];
 extern volatile int pending_save_slots[MAX_SLOTS];
-extern volatile int latest_eapol_count;
+extern volatile uint8_t latest_eapol_count[MAX_SLOTS];
 extern bool is_capturing;
 extern int current_channel;
 extern CapturePhase capturePhase;
@@ -78,4 +85,3 @@ void stopCapture();
 bool isCaptureable(int index);
 void handshakeCaptureLoop();
 int getCaptureableCount();
-int getBestChannel();