Fix build error and add stronger soft keyboard suppression

Replace BuildConfig.DEBUG (not generated by AGP 8.x) with unconditional
WebView debugging — safe for a kiosk app since it requires ADB access.

Add two additional layers of keyboard suppression for devices where the
null InputConnection alone is insufficient: inject JavaScript that sets
inputmode="none" on all inputs via MutationObserver, and force-hide the
keyboard via InputMethodManager on page load and window focus changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/main/java/mx/joykoo/scanner/MainActivity.kt

@@ -15,6 +15,7 @@ import android.view.View
 import android.view.WindowInsets
 import android.view.WindowInsetsController
 import android.view.WindowManager
+import android.view.inputmethod.InputMethodManager
 import android.webkit.ConsoleMessage
 import android.webkit.CookieManager
 import android.webkit.SslErrorHandler
@@ -88,7 +89,10 @@ class MainActivity : AppCompatActivity() {
 
     override fun onWindowFocusChanged(hasFocus: Boolean) {
         super.onWindowFocusChanged(hasFocus)
-        if (hasFocus) enterImmersiveMode()
+        if (hasFocus) {
+            enterImmersiveMode()
+            hideKeyboard()
+        }
     }
 
     // ── WebView Setup ───────────────────────────────────────────────────
@@ -131,7 +135,7 @@ class MainActivity : AppCompatActivity() {
             setAcceptThirdPartyCookies(webView, true)
         }
 
-        WebView.setWebContentsDebuggingEnabled(BuildConfig.DEBUG)
+        WebView.setWebContentsDebuggingEnabled(true)
 
         webView.webViewClient = ScannerWebViewClient()
         webView.webChromeClient = ScannerWebChromeClient()
@@ -286,6 +290,42 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private fun hideKeyboard() {
+        val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
+        imm.hideSoftInputFromWindow(webView.windowToken, 0)
+    }
+
+    private fun injectKeyboardSuppression(view: WebView) {
+        view.evaluateJavascript("""
+            (function() {
+                if (window.__jkKbSuppressed) return;
+                window.__jkKbSuppressed = true;
+                function suppress(el) {
+                    if (el.tagName === 'INPUT' || el.tagName === 'TEXTAREA'
+                        || el.isContentEditable) {
+                        el.setAttribute('inputmode', 'none');
+                        el.setAttribute('autocomplete', 'off');
+                    }
+                }
+                document.querySelectorAll('input, textarea, [contenteditable]')
+                    .forEach(suppress);
+                new MutationObserver(function(muts) {
+                    muts.forEach(function(m) {
+                        m.addedNodes.forEach(function(n) {
+                            if (n.nodeType === 1) {
+                                suppress(n);
+                                if (n.querySelectorAll)
+                                    n.querySelectorAll('input, textarea, [contenteditable]')
+                                        .forEach(suppress);
+                            }
+                        });
+                    });
+                }).observe(document.body || document.documentElement,
+                    { childList: true, subtree: true });
+            })();
+        """.trimIndent(), null)
+    }
+
     // ── WebViewClient ───────────────────────────────────────────────────
 
     private inner class ScannerWebViewClient : WebViewClient() {
@@ -311,6 +351,8 @@ class MainActivity : AppCompatActivity() {
         override fun onPageFinished(view: WebView, url: String?) {
             super.onPageFinished(view, url)
             CookieManager.getInstance().flush()
+            injectKeyboardSuppression(view)
+            hideKeyboard()
             ensureWebViewFocus()
         }