fix(android): split LoginScreen into LoginForm + SubmitButton (detekt LongMethod)

LoginScreen body was 76 lines vs the 60 cap. Pulled the centered
Column into LoginForm() and the spin-aware Button into SubmitButton().
LoginScreen is back to ~20 lines (LaunchedEffect + Box around LoginForm).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/auth/ui/LoginScreen.kt

@@ -46,68 +46,88 @@ fun LoginScreen(
     }
 
     Box(modifier = Modifier.fillMaxSize()) {
-        Column(
-            modifier = Modifier
-                .fillMaxSize()
-                .padding(24.dp),
-            verticalArrangement = Arrangement.spacedBy(16.dp, Alignment.CenterVertically),
-            horizontalAlignment = Alignment.CenterHorizontally,
-        ) {
+        LoginForm(
+            state = state,
+            onUsernameChange = viewModel::setUsername,
+            onPasswordChange = viewModel::setPassword,
+            onSubmit = viewModel::submit,
+        )
+    }
+}
+
+@Composable
+private fun LoginForm(
+    state: LoginFormState,
+    onUsernameChange: (String) -> Unit,
+    onPasswordChange: (String) -> Unit,
+    onSubmit: () -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.spacedBy(16.dp, Alignment.CenterVertically),
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = "Sign in",
+            style = MaterialTheme.typography.headlineMedium,
+            color = MaterialTheme.colorScheme.onBackground,
+        )
+        OutlinedTextField(
+            value = state.username,
+            onValueChange = onUsernameChange,
+            modifier = Modifier.fillMaxWidth(),
+            label = { Text("Username") },
+            singleLine = true,
+            enabled = !state.isSubmitting,
+            keyboardOptions = KeyboardOptions(
+                keyboardType = KeyboardType.Email,
+                imeAction = ImeAction.Next,
+            ),
+        )
+        OutlinedTextField(
+            value = state.password,
+            onValueChange = onPasswordChange,
+            modifier = Modifier.fillMaxWidth(),
+            label = { Text("Password") },
+            singleLine = true,
+            enabled = !state.isSubmitting,
+            visualTransformation = PasswordVisualTransformation(),
+            keyboardOptions = KeyboardOptions(
+                keyboardType = KeyboardType.Password,
+                imeAction = ImeAction.Done,
+            ),
+            keyboardActions = KeyboardActions(onDone = { onSubmit() }),
+        )
+        if (state.errorMessage != null) {
             Text(
-                text = "Sign in",
-                style = MaterialTheme.typography.headlineMedium,
-                color = MaterialTheme.colorScheme.onBackground,
+                text = state.errorMessage,
+                color = MaterialTheme.colorScheme.error,
+                style = MaterialTheme.typography.bodySmall,
             )
-            OutlinedTextField(
-                value = state.username,
-                onValueChange = viewModel::setUsername,
-                modifier = Modifier.fillMaxWidth(),
-                label = { Text("Username") },
-                singleLine = true,
-                enabled = !state.isSubmitting,
-                keyboardOptions = KeyboardOptions(
-                    keyboardType = KeyboardType.Email,
-                    imeAction = ImeAction.Next,
-                ),
+        }
+        SubmitButton(state = state, onSubmit = onSubmit)
+    }
+}
+
+@Composable
+private fun SubmitButton(state: LoginFormState, onSubmit: () -> Unit) {
+    Button(
+        onClick = onSubmit,
+        enabled = !state.isSubmitting &&
+            state.username.isNotBlank() &&
+            state.password.isNotBlank(),
+        modifier = Modifier.fillMaxWidth(),
+    ) {
+        if (state.isSubmitting) {
+            CircularProgressIndicator(
+                modifier = Modifier.size(20.dp),
+                color = MaterialTheme.colorScheme.onPrimary,
+                strokeWidth = 2.dp,
             )
-            OutlinedTextField(
-                value = state.password,
-                onValueChange = viewModel::setPassword,
-                modifier = Modifier.fillMaxWidth(),
-                label = { Text("Password") },
-                singleLine = true,
-                enabled = !state.isSubmitting,
-                visualTransformation = PasswordVisualTransformation(),
-                keyboardOptions = KeyboardOptions(
-                    keyboardType = KeyboardType.Password,
-                    imeAction = ImeAction.Done,
-                ),
-                keyboardActions = KeyboardActions(onDone = { viewModel.submit() }),
-            )
-            if (state.errorMessage != null) {
-                Text(
-                    text = state.errorMessage.orEmpty(),
-                    color = MaterialTheme.colorScheme.error,
-                    style = MaterialTheme.typography.bodySmall,
-                )
-            }
-            Button(
-                onClick = viewModel::submit,
-                enabled = !state.isSubmitting &&
-                    state.username.isNotBlank() &&
-                    state.password.isNotBlank(),
-                modifier = Modifier.fillMaxWidth(),
-            ) {
-                if (state.isSubmitting) {
-                    CircularProgressIndicator(
-                        modifier = Modifier.size(20.dp),
-                        color = MaterialTheme.colorScheme.onPrimary,
-                        strokeWidth = 2.dp,
-                    )
-                } else {
-                    Text("Sign in")
-                }
-            }
+        } else {
+            Text("Sign in")
         }
     }
 }