chore(07-06): land the quick-task 261024-001 logo-asset replacement residue

- /start sendPhoto now points at MASTER_FILE-arah2_logo.png (deployed
  from web/public/ — the untracked asset lands here so the reference
  resolves on deploy)
- README + AGENTS.md + the 4 mockup screens swapped the Stitch
  googleusercontent logo placeholder for the local master logo
- pre-existing on the tree through 07-03..07-05 execution; verified by
  this session's baselines (bot 126/126, web 165/165, captures 22/22)

bot/src/bot/commands/start.ts

@@ -9,11 +9,12 @@
  * payloads, no callback routes anywhere in this tree.
  *
  * Device-gate feedback (2026-10-24): /start now carries the app logo —
- * sendPhoto by its STATIC-ASSET public URL (<MINI_APP_URL>/logo_arah2.png,
- * deployed from web/public/). Telegram fetches it server-side; the repo
- * asset stays the single source (assets/logo_arah2.png). Photo send is
- * resilient: if the fetch/send fails (e.g. asset not deployed yet), the
- * text reply still goes out — the greeting is never lost.
+ * sendPhoto by its STATIC-ASSET public URL
+ * (<MINI_APP_URL>/MASTER_FILE-arah2_logo.png, deployed from web/public/).
+ * The repo asset stays the single source
+ * (assets/MASTER_FILE-arah2_logo.png). Photo send is resilient: if the
+ * fetch/send fails (e.g. asset not deployed yet), the text reply still
+ * goes out — the greeting is never lost.
  *
  * All copy comes from src/i18n/strings.ts (D-05) — nothing inline here.
  */
@@ -32,7 +33,7 @@ export function startReplyText(locale: Locale): string {
 export function startLogoUrl(origin: string | undefined): string | null {
   if (!origin) return null;
   try {
-    return `${new URL(origin).origin}/logo_arah2.png`;
+    return `${new URL(origin).origin}/MASTER_FILE-arah2_logo.png`;
   } catch {
     return null;
   }