Disable location sharing when no MapTiler config is available

LocationService now exposes the MapTiler config to use: the one provided by the
homeserver takes precedence over the build time one, and null means that no map
provider is configured. It is now session scoped, and isServiceAvailable()
returns a StateFlow derived from this config.

When no config is available:
- the location sharing option is hidden from the composer, and location events
  cannot be opened in the location viewer;
- the "Location sharing" entry is hidden from the settings;
- location events in the timeline render a placeholder, without performing any
  request to MapTiler.

The show and share location screens now get the config from LocationService
rather than fetching the homeserver config by themselves.

Closes element-hq/element-android-enterprise#69

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

features/location/api/src/main/kotlin/io/element/android/features/location/api/LocalMapTilerConfig.kt

@@ -11,13 +11,22 @@ import androidx.compose.runtime.staticCompositionLocalOf
 import io.element.android.features.enterprise.api.remoteconfig.MapTilerConfig
 
 /**
- * Provides a [MapTilerConfig] for the MapLibre maps.
+ * Provides the [MapTilerConfig] for the MapLibre maps, or null if no map provider is configured.
  */
-val LocalMapTilerConfig = staticCompositionLocalOf {
-    MapTilerConfig(
-        apiKey = BuildConfig.MAPTILER_API_KEY,
-        lightStyleId = BuildConfig.MAPTILER_LIGHT_MAP_ID,
-        darkStyleId = BuildConfig.MAPTILER_DARK_MAP_ID,
-        baseUrl = BuildConfig.MAPTILER_BASE_URL
-    )
+val LocalMapTilerConfig = staticCompositionLocalOf { buildTimeMapTilerConfig() }
+
+/**
+ * The [MapTilerConfig] defined at build time, or null if no MapTiler API key has been provided.
+ */
+fun buildTimeMapTilerConfig(): MapTilerConfig? {
+    return BuildConfig.MAPTILER_API_KEY
+        .takeIf { it.isNotEmpty() }
+        ?.let { apiKey ->
+            MapTilerConfig(
+                apiKey = apiKey,
+                lightStyleId = BuildConfig.MAPTILER_LIGHT_MAP_ID,
+                darkStyleId = BuildConfig.MAPTILER_DARK_MAP_ID,
+                baseUrl = BuildConfig.MAPTILER_BASE_URL
+            )
+        }
 }

features/location/api/src/main/kotlin/io/element/android/features/location/api/LocationService.kt

@@ -8,10 +8,21 @@
 
 package io.element.android.features.location.api
 
+import io.element.android.features.enterprise.api.remoteconfig.MapTilerConfig
+import io.element.android.libraries.core.coroutine.mapState
+import kotlinx.coroutines.flow.StateFlow
+
 /**
- * Tells whether the location features can be used at all, which depends on the build having a map provider configured.
+ * Tells whether the location features can be used at all, which depends on a map provider being configured,
+ * either by the homeserver or at build time.
  */
 interface LocationService {
+    /**
+     * The [MapTilerConfig] to use to render the maps, or null if no map provider is configured.
+     * The configuration provided by the homeserver takes precedence over the one defined at build time.
+     */
+    val mapTilerConfig: StateFlow<MapTilerConfig?>
+
     /** Whether location sharing and map rendering are available; `false` disables the whole feature in the UI. */
-    fun isServiceAvailable(): Boolean
+    fun isServiceAvailable(): StateFlow<Boolean> = mapTilerConfig.mapState { it != null }
 }

features/location/api/src/main/kotlin/io/element/android/features/location/api/StaticMapView.kt

@@ -50,11 +50,12 @@ import io.element.android.libraries.designsystem.utils.CommonDrawables
 /**
  * Shows a static map image downloaded via a third party service's static maps API.
  *
- * Handles 4 distinct cases:
+ * Handles 5 distinct cases:
  * 1. Stale location (pinVariant is StaleLocation) - shows stale map with stale pin, no fetching
  * 2. Null location - shows blurred placeholder, no pin, no loading
- * 3. Loading (location != null, fetching) - shows blurred placeholder with loading indicator
- * 4. Success (location != null, loaded) - shows actual map with pin
+ * 3. Null mapTilerConfig (no map provider configured) - shows blurred placeholder, no pin, no fetching
+ * 4. Loading (location != null, fetching) - shows blurred placeholder with loading indicator
+ * 5. Success (location != null, loaded) - shows actual map with pin
  */
 @Composable
 fun StaticMapView(
@@ -84,7 +85,8 @@ fun StaticMapView(
                 )
             }
             // Case 2: Null location - show blurred placeholder, no pin, no loading
-            location == null -> {
+            // Case 3: No map provider configured - show blurred placeholder, no pin, no fetching
+            location == null || mapTilerConfig == null && !LocalInspectionMode.current -> {
                 StaticMapPlaceholder(
                     painter = painterResource(R.drawable.blurred_map),
                     canReload = false,
@@ -94,7 +96,7 @@ fun StaticMapView(
                     onLoadMapClick = {}
                 )
             }
-            // Cases 3 & 4: Non-null location - fetch map
+            // Cases 4 & 5: Non-null location - fetch map
             else -> LoadableMapContent(
                 mapTilerConfig = mapTilerConfig,
                 location = location,