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>

src/main.cpp

@@ -205,7 +205,7 @@ static void enter_provisioning(const String& mac, bool retry = false) {
     suffix.replace(":", "");
     suffix = suffix.substring(suffix.length() - 4);
     suffix.toUpperCase();
-    String apSsid = "PictureFrame-" + suffix;
+    String apSsid = "WeVisto-" + suffix;
 
     Serial.println(retry ? "AP (retry): " + apSsid : "AP: " + apSsid);
 

src/operation.h

@@ -72,7 +72,7 @@ inline String ap_ssid_from_mac(const String& mac) {
         ++p;
     }
     std::string suffix = cleaned.substr(cleaned.size() - 4);
-    return String(("PictureFrame-" + suffix).c_str());
+    return String(("WeVisto-" + suffix).c_str());
 }
 
 // ── WiFi connection attempt ───────────────────────────────────────────────────