feat(brand): AP SSID WeVisto-XXXX + logo placeholder + 4-step copy

Rename the AP broadcast SSID from PictureFrame-XXXX to WeVisto-XXXX
(operation.h:ap_ssid_from_mac + main.cpp:enter_provisioning). Tests
updated to match.

Setup screens (both panels):
- Top-right header chip replaced with a draw_logo_placeholder() box —
  a 'WeVisto' text mark with a 'PLACEHOLDER' subtitle. When the real
  brand asset lands, swap the function for a paste of the file at the
  same coordinates; no layout change needed.
- Step list rewritten to Matt's spec (4 steps, not 5):
    1. Turn on your WeVisto
    2. Unlock your phone
    3. Scan QR 1  — This will connect your phone to the WeVisto
    4. Scan QR 2  — This will open the WeVisto setup page
  Step 5 (type WiFi password) lived only in the on-panel guide; the
  user does that on the phone via the captive portal, where the
  prompt is already explicit.
- Regenerated both panels' setup_bg / ap_bg / ap_bg_retry assets via
  the gen_screens scripts.

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

test/test_normal_operation/test_main.cpp

@@ -646,12 +646,12 @@ void test_fw_draw_pending_header_absent_when_no_draw_needed() {
 // FW-12/13: AP SSID derivation via ap_ssid_from_mac()
 void test_fw12_ap_ssid_from_mac_aabbcc() {
     String ssid = ap_ssid_from_mac(String("AA:BB:CC:DD:EE:FF"));
-    TEST_ASSERT_EQUAL_STRING("PictureFrame-EEFF", ssid.c_str());
+    TEST_ASSERT_EQUAL_STRING("WeVisto-EEFF", ssid.c_str());
 }
 
 void test_fw13_ap_ssid_from_real_mac() {
     String ssid = ap_ssid_from_mac(String("1C:C3:AB:D1:91:F8"));
-    TEST_ASSERT_EQUAL_STRING("PictureFrame-91F8", ssid.c_str());
+    TEST_ASSERT_EQUAL_STRING("WeVisto-91F8", ssid.c_str());
 }
 
 int main(int argc, char** argv) {