Fix architecture diagram issues

- Changed Core Backend to 'Go (REST API)' (removed gRPC, kept REST)
- Removed BLE from IoT (not supported yet)
- Fixed text overflow in boxes by adjusting layout and labels
- Updated description to reflect REST-only API

TallyFlow/TallyFlow-Architecture-Diagram.html

@@ -92,8 +92,8 @@
         <!-- Core Backend (Go) - CENTER -->
         <rect x="410" y="100" width="200" height="70" rx="8" fill="rgba(6, 78, 59, 0.55)" stroke="#34d399" stroke-width="2"/>
         <text x="510" y="127" fill="white" font-size="13" font-weight="700" text-anchor="middle">Core Backend</text>
-        <text x="510" y="145" fill="#94a3b8" font-size="10" text-anchor="middle">Go (Echo / gRPC)</text>
-        <text x="510" y="161" fill="#34d399" font-size="9" text-anchor="middle">REST + WebSocket API</text>
+        <text x="510" y="145" fill="#94a3b8" font-size="10" text-anchor="middle">Go (REST API)</text>
+        <text x="510" y="161" fill="#34d399" font-size="9" text-anchor="middle">REST + WebSocket</text>
 
         <!-- MongoDB (nested inside Core) - RIGHT -->
         <rect x="630" y="100" width="170" height="70" rx="6" fill="rgba(76, 29, 149, 0.6)" stroke="#a78bfa" stroke-width="1.5"/>
@@ -130,7 +130,7 @@
         <text x="810" y="408" fill="white" font-size="13" font-weight="700" text-anchor="middle">IoT</text>
         <text x="810" y="426" fill="#94a3b8" font-size="10" text-anchor="middle">Rust</text>
         <text x="810" y="444" fill="#fb923c" font-size="9" text-anchor="middle">Fixed Readers • Sensors</text>
-        <text x="810" y="460" fill="#94a3b8" font-size="8" text-anchor="middle">MQTT / HTTP / BLE • ERP integration</text>
+        <text x="810" y="460" fill="#94a3b8" font-size="8" text-anchor="middle">MQTT / HTTP • ERP integration</text>
 
         <!-- ========== CONNECTIONS ========== -->