feat: Update Android architecture

[iTEEECH]

Update Android architecture

Description

Android Wi‑Fi behavior in wifi_iot and wifi_scan has changed significantly since API 29 (Android 10). Connection, network registration, SSID/IP resolution, and scan result access no longer work reliably when everything stays in one monolithic plugin class that mixes legacy WifiConfiguration / WifiManager APIs with modern WifiNetworkSpecifier / WifiNetworkSuggestion / ConnectivityManager paths.

On current Android versions (especially 12+ / API 31+ and 13+ / API 33+), apps commonly hit:

• Deprecated or restricted STA APIs for connect / disconnect / register
•  / unreadable SSID when reading only WifiManager.getConnectionInfo() or a single joinedNetwork
• Incorrect or missing SSID from scan results when still relying on deprecated ScanResult.SSID on API 33+
• BroadcastReceiver registration requirements on API 33+ (RECEIVER_NOT_EXPORTED)
• Hard-to-maintain Android code: legacy and modern logic interleaved inside WifiIotPlugin

Why changes

• Platform fragmentation — Pre‑Q devices still need WifiConfiguration / addNetwork / enableNetwork. API 29+ requires WifiNetworkSpecifier (local / no internet) or WifiNetworkSuggestion (with internet), plus proper NetworkCallback lifecycle handling.
• SSID / IP reliability on Android 12+ — With concurrent networks and privacy restrictions, SSID and IPv4 must be resolved from ConnectivityManager Wi‑Fi networks (prefer joined, then active, then others), not only from the legacy connection-info path.
• Maintainability — WifiIotPlugin owned both Flutter channel plumbing and all STA backends. That made API‑level branching error-prone and blocked safe evolution of modern Android support.
• Scan API modernization — wifi_scan must follow current Android rules for receivers, throttled startScan(), fine location, and SSID extraction via wifiSsid on API 33+.
• Production impact — Apps that connect to instrument / lab / IoT networks (including no-internet Wi‑Fi) need stable connect/disconnect and readable SSID across OEM builds and recent Android releases.

Solutions

API level	Implementation	Role
API < 29	LegacyWifiPlatform	WifiConfiguration, legacy connect/disconnect/register
API ≥ 29	ModernWifiPlatform	Specifier / suggestion, NetworkCallback, modern SSID/IP

It may be released in development mode to gather feedback before the official release.

Tested on Android 11 and Android 16