Add user PIN protection (#719)

## Description
Adds (back) the ability to set a per-user PIN. This is required to
switch to the user. If the user has a PIN, this overrides and ignores
the "Sign in automatically" setting for that user.

The PIN consists of any combination of D-Pad directional buttons. If you
forget the PIN, you can click the button to login via the server instead
(ie QuickConnect or username/password) which will also remove the PIN so
you can set a new one if desired.

### Related issues
Closes #268 
Replaces #398
Related to #321 & #356

### Screenshots
![enter_pin
Large](https://github.com/user-attachments/assets/aa25364d-1266-410d-846e-8dc32c56a794)

app/src/main/java/com/github/damontecres/wholphin/MainActivity.kt

@@ -3,6 +3,7 @@ package com.github.damontecres.wholphin
 import android.content.Intent
 import android.content.res.Configuration
 import android.os.Bundle
+import android.view.WindowManager
 import androidx.activity.compose.setContent
 import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
@@ -138,6 +139,16 @@ class MainActivity : AppCompatActivity() {
                 window.attributes = attrs.apply { preferredDisplayModeId = modeId }
             }
         }
+        viewModel.serverRepository.currentUser.observe(this) { user ->
+            if (user?.hasPin == true) {
+                window?.setFlags(
+                    WindowManager.LayoutParams.FLAG_SECURE,
+                    WindowManager.LayoutParams.FLAG_SECURE,
+                )
+            } else {
+                window?.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
+            }
+        }
         viewModel.appStart()
         val requestedDestination = this.intent?.let(::extractDestination)
         setContent {
@@ -292,14 +303,6 @@ class MainActivity : AppCompatActivity() {
         super.onRestart()
         Timber.d("onRestart")
         viewModel.appStart()
-//        val signInAutomatically =
-//            runBlocking { userPreferencesDataStore.data.firstOrNull()?.signInAutomatically } ?: true
-
-//        // TODO PIN-related
-// //        if (!signInAutomatically || serverRepository.currentUser.value?.hasPin == true) {
-//        if (!signInAutomatically) {
-//            serverRepository.closeSession()
-//        }
     }
 
     override fun onStop() {
@@ -392,7 +395,7 @@ class MainActivityViewModel
     @Inject
     constructor(
         private val preferences: DataStore<AppPreferences>,
-        private val serverRepository: ServerRepository,
+        val serverRepository: ServerRepository,
         private val navigationManager: SetupNavigationManager,
         private val deviceProfileService: DeviceProfileService,
         private val backdropService: BackdropService,
@@ -402,7 +405,8 @@ class MainActivityViewModel
                 try {
                     val prefs =
                         preferences.data.firstOrNull() ?: AppPreferences.getDefaultInstance()
-                    if (prefs.signInAutomatically) {
+                    val userHasPin = serverRepository.currentUser.value?.hasPin == true
+                    if (prefs.signInAutomatically && !userHasPin) {
                         val current =
                             serverRepository.restoreSession(
                                 prefs.currentServerId?.toUUIDOrNull(),

app/src/main/java/com/github/damontecres/wholphin/data/ServerRepository.kt

@@ -142,8 +142,6 @@ class ServerRepository
                 } else {
                     val user = serverAndUsers.users.firstOrNull { it.id == userId }
                     if (user != null) {
-                        // TODO pin-related
-//                if (user != null && !user.hasPin) {
                         return changeUser(serverAndUsers.server, user)
                     }
                 }

app/src/main/java/com/github/damontecres/wholphin/preferences/AppPreference.kt

@@ -932,8 +932,7 @@ val basicPreferences =
             title = R.string.profile_specific_settings,
             preferences =
                 listOf(
-                    // TODO PIN-related
-                    // AppPreference.RequireProfilePin,
+                    AppPreference.RequireProfilePin,
                     AppPreference.UserPinnedNavDrawerItems,
                 ),
         ),

app/src/main/java/com/github/damontecres/wholphin/ui/setup/SwitchUserContent.kt

@@ -118,13 +118,11 @@ fun SwitchUserContent(
                     users = users,
                     currentUser = currentUser,
                     onSwitchUser = { user ->
-                        // TODO PIN-related
-//                        if (user.pin.isNotNullOrBlank()) {
-//                            switchUserWithPin = user
-//                        } else {
-//                            viewModel.switchUser(user)
-//                        }
+                        if (user.hasPin) {
+                            switchUserWithPin = user
+                        } else {
                             viewModel.switchUser(user)
+                        }
                     },
                     onAddUser = { showAddUser = true },
                     onRemoveUser = { user ->