Implement full TollGate display UI

- BOOT screen: centered title + WiFi status line
- READY screen: QR cycling (WiFi/Portal), price, mint domain,
  wallet balance (color-coded), client count
- PAYMENT screen: green banner 'ACCESS GRANTED', paid amount, time
- ERROR screen: red banner 'NO UPSTREAM', guidance, AP reassurance
- Enhanced display_update() API with mint_url, price, wifi_status
- Extract domain helper for clean mint URL display
- Render interval: 2s (reduced SPI load)
- Color palette: cyan, yellow, orange, green, red, dim gray
- WiFi events update display status and trigger ERROR state
- Board C now on /dev/ttyACM3

1 files changed, 3 insertions, 1 deletions

diff --git a/main/display.h b/main/display.h
index 407521b..1530e57 100644
--- a/main/display.h
+++ b/main/display.h
@@ -20,7 +20,9 @@ typedef enum {
 esp_err_t display_init(void);
 void display_set_state(display_state_t state);
 void display_update(const char *ap_ssid, int active_clients,
-                    uint64_t wallet_balance, const char *portal_url);
+                    uint64_t wallet_balance, const char *portal_url,
+                    const char *mint_url, int price_per_step,
+                    const char *wifi_status);
 void display_render_text(int x, int y, const char *text, uint16_t fg, uint16_t bg, int scale);
 void display_render_qr(const char *text);