Run executables directly (#645)

- Apps can be launched directly from file paths (including Files app support)
- Added executable detection to identify unsupported or invalid binaries before launch.
- App startup is now streamlined through separate registered-app and direct-execution interfaces.
- Existing app launch points were migrated to the updated startup APIs.

Modules/app-module/include/app/execute.h

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+/**
+ * This file contains functions to start and run apps.
+ * It differs from start.h by running apps directly from the specified location,
+ * instead of having to register them first via an AppManifest and the app manager.
+ */
+
+#include <app/manager.h>
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Starts an app directly from @a location, without it having to be pre-registered via
+ * app_manager_add() first.
+ * Performs no checks of its own beyond what AppLoaderApi::load() itself rejects.
+ * @warning It's advised to validate @a location with app_is_executable() first
+ * @param[in] stack stack allocation config for the app's task; all-zero uses the scheduler's
+ * default depth/capability, same as an AppManifest that leaves AppManifest::stack zeroed
+ * @retval ERROR_NOT_FOUND no AppLoaderApi is registered for @a location.type
+ * @retval ERROR_NONE on success
+ */
+error_t app_execute(
+    struct AppLocation location,
+    struct AppStackConfig stack,
+    int argc,
+    const char* const argv[],
+    AppInstanceId* out_app_instance_id
+);
+
+/**
+ * Same as app_execute(), but as a modal child of @a parent_instance_id.
+ * See app_start_for_result()'s own doc for the result-delivery contract.
+ * @retval ERROR_NOT_FOUND no AppLoaderApi is registered for @a location.type
+ * @retval ERROR_NONE on success
+ */
+error_t app_execute_for_result(
+    struct AppLocation location,
+    struct AppStackConfig stack,
+    int argc,
+    const char* const argv[],
+    AppInstanceId parent_instance_id,
+    AppInstanceId* out_app_instance_id
+);
+
+/**
+ * Same as app_execute(), but installs @a bindings into the new instance's fd table before its
+ * task begins executing. See app_start_with_streams()'s own doc for stream ownership.
+ * @param[in] bindings see app_start_with_streams()
+ * @retval ERROR_NOT_FOUND no AppLoaderApi is registered for @a location.type
+ * @retval ERROR_OUT_OF_RANGE a binding's producer_fd is out of range
+ * @retval ERROR_RESOURCE a binding's event_group has no free bits left to claim
+ * @retval ERROR_NONE on success
+ */
+error_t app_execute_with_streams(
+    struct AppLocation location,
+    struct AppStackConfig stack,
+    int argc,
+    const char* const argv[],
+    const struct AppStreamBinding* bindings,
+    size_t binding_count,
+    AppInstanceId* out_app_instance_id
+);
+
+/**
+ * Combines app_execute_for_result() and app_execute_with_streams().
+ * @param[in] bindings see app_start_with_streams()
+ * @retval ERROR_NOT_FOUND no AppLoaderApi is registered for @a location.type
+ * @retval ERROR_OUT_OF_RANGE a binding's producer_fd is out of range
+ * @retval ERROR_RESOURCE a binding's event_group has no free bits left to claim
+ * @retval ERROR_NONE on success
+ */
+error_t app_execute_for_result_with_streams(
+    struct AppLocation location,
+    struct AppStackConfig stack,
+    int argc,
+    const char* const argv[],
+    const struct AppStreamBinding* bindings,
+    size_t binding_count,
+    AppInstanceId parent_instance_id,
+    AppInstanceId* out_app_instance_id
+);
+
+/**
+ * Reports whether @a location is runnable on this target: the extension and header a loader
+ * requires (e.g. an ELF's class/data/type/machine), not whether it lives anywhere in particular.
+ * Any executable app is runnable from any path. Cheap enough to call while listing a directory.
+ * @return false if @a location can't be run, or if no AppLoaderApi is registered for its type
+ */
+bool app_is_executable(struct AppLocation location);
+
+#ifdef __cplusplus
+}
+#endif