fix(operation): EXT0 wakeup on BOOT button so 5-sec-hold reset works during sleep

Bug: the device only woke from deep sleep on a timer; pressing BOOT
during sleep did nothing. The 5-second-hold reset only worked in the
brief awake window during a poll, which made the documented "hold BOOT
to reset" gesture appear broken to the user. Reported live 2026-05-09.

Fix: arm EXT0 wakeup on PIN_BTN_RESET (active-low — BOOT is pulled-up
on the dev board) at every esp_deep_sleep_start. After the press wakes
the chip, setup() runs and the existing check_reset_button() handles
the rest of the 5-second hold and triggers the NVS clear + reprovision.

Mocks: esp_sleep.h gains gpio_num_t typedef + g_ext0_wakeup_pin/level
globals so the native test can assert the call shape.

Test: FW-RESET-WAKE pins the contract — every deep_sleep_start must
arm EXT0 on PIN_BTN_RESET, level 0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/mocks/esp_sleep.h

@@ -3,6 +3,8 @@
 
 extern uint64_t g_sleep_us;
 extern bool     g_deep_sleep_started;
+extern int      g_ext0_wakeup_pin;
+extern int      g_ext0_wakeup_level;
 
 // Mirror of the ESP-IDF wakeup-cause enum that the firmware actually checks.
 // Tests set g_wakeup_cause directly to simulate cold-boot vs timer-wake.
@@ -17,6 +19,17 @@ typedef enum {
 
 extern esp_sleep_wakeup_cause_t g_wakeup_cause;
 
+// gpio_num_t alias for the wakeup helper. The real header is part of
+// esp-idf; for native tests we just use int.
+typedef int gpio_num_t;
+#ifndef GPIO_NUM_0
+#define GPIO_NUM_0 0
+#endif
+
 inline void esp_sleep_enable_timer_wakeup(uint64_t us) { g_sleep_us = us; }
+inline void esp_sleep_enable_ext0_wakeup(gpio_num_t pin, int level) {
+    g_ext0_wakeup_pin   = pin;
+    g_ext0_wakeup_level = level;
+}
 inline void esp_deep_sleep_start() { g_deep_sleep_started = true; }
 inline esp_sleep_wakeup_cause_t esp_sleep_get_wakeup_cause() { return g_wakeup_cause; }

test/test_normal_operation/test_main.cpp

@@ -35,6 +35,8 @@ int g_epd_draw_border_count, g_epd_draw_border_last_color, g_epd_draw_border_las
 uint64_t g_sleep_us;
 bool g_deep_sleep_started;
 esp_sleep_wakeup_cause_t g_wakeup_cause;
+int g_ext0_wakeup_pin;
+int g_ext0_wakeup_level;
 
 // Globals for new mocks
 int      g_show_setup_qr_count;
@@ -68,6 +70,8 @@ void reset_state() {
     g_sleep_us = 0;
     g_deep_sleep_started = false;
     g_wakeup_cause = ESP_SLEEP_WAKEUP_TIMER; // default to timer wake unless a test sets cold
+    g_ext0_wakeup_pin = -1;
+    g_ext0_wakeup_level = -1;
     g_show_setup_qr_count = 0;
     g_millis_value = 0;
     g_digital_read_value = HIGH;  // button not pressed by default
@@ -352,6 +356,17 @@ void test_fw_X_Claimed_response_clears_flag() {
     TEST_ASSERT_EQUAL(0, prefs.getInt(NVS_KEY_JUST_PROVISIONED, -1));
 }
 
+// FW-RESET-WAKE: every deep-sleep cycle must arm EXT0 wakeup on the BOOT
+// button, otherwise holding it during sleep does nothing and the user-
+// facing 5-second-hold reset only works during the brief awake window.
+// Reported live by Matt 2026-05-09: held BOOT, device didn't reset.
+void test_fw_deep_sleep_arms_ext0_button_wakeup() {
+    g_http_response_headers["X-Image-Id"] = "1";
+    normal_operation_impl(String("mac"), http, String("url"), prefs);
+    TEST_ASSERT_EQUAL(PIN_BTN_RESET, g_ext0_wakeup_pin);
+    TEST_ASSERT_EQUAL(0, g_ext0_wakeup_level); // active-low; BOOT is pulled-up
+}
+
 // FW-FIRST-IMG-A: device has never received an image (img_id = -1) AND the
 // poll didn't deliver one (e.g. 204 because no images approved yet). Sleep
 // must be the 15s bootstrap interval, NOT whatever the server's schedule
@@ -526,6 +541,7 @@ int main(int argc, char** argv) {
     RUN_TEST(test_fw_first_image_bootstrap_polls_at_15s_when_no_image_yet);
     RUN_TEST(test_fw_first_image_bootstrap_clears_after_200);
     RUN_TEST(test_fw_first_image_just_arrived_uses_server_interval);
+    RUN_TEST(test_fw_deep_sleep_arms_ext0_button_wakeup);
     RUN_TEST(test_fw12_ap_ssid_from_mac_aabbcc);
     RUN_TEST(test_fw13_ap_ssid_from_real_mac);
     RUN_TEST(test_fw14_304_skips_epd_sleep);