fix(firmware): make QEMU mock CSI boot successfully on Windows

Tested on Windows with Espressif QEMU 9.0.0 — firmware boots,
generates mock CSI frames, runs edge processing. 14/16 validation
checks pass.

Fixes:
- Guard wifi_init_sta() with CONFIG_CSI_MOCK_SKIP_WIFI_CONNECT
  (QEMU has no RF PHY, WiFi init stalled at calibration)
- Guard stream_sender_init_with() (UDP needs network stack)
- Guard ota_update_init_ex() (HTTP server needs network)
- Guard display_task_start() with CONFIG_DISPLAY_ENABLE
  (no I2C hardware in QEMU)
- Add mock_csi_init() call in main.c when CONFIG_CSI_MOCK_ENABLED
- Add #include "sdkconfig.h" to mock_csi.c (ESP-IDF not auto-including)
- Suppress unused s_bad_mac warning

Co-Authored-By: claude-flow <ruv@ruv.net>

firmware/esp32-csi-node/main/mock_csi.c

@@ -15,6 +15,8 @@
  * to nothing on production builds.
  */
 
+#include "sdkconfig.h"
+
 #ifdef CONFIG_CSI_MOCK_ENABLED
 
 #include "mock_csi.h"
@@ -94,7 +96,7 @@ static const uint8_t s_sweep_channels[] = {1, 6, 11, 36};
 static const uint8_t s_good_mac[6] = {0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};
 
 /** "Wrong" MAC that should be rejected by the filter. */
-static const uint8_t s_bad_mac[6]  = {0x11, 0x22, 0x33, 0x44, 0x55, 0x66};
+static const uint8_t s_bad_mac[6] __attribute__((unused)) = {0x11, 0x22, 0x33, 0x44, 0x55, 0x66};
 
 /* ---- LFSR pseudo-random number generator ---- */