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/elf_check.h

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// <elf.h> is not guaranteed to exist under the ESP32 newlib toolchain
+#define ELF_CLASS_32 1
+#define ELF_CLASS_64 2
+#define ELF_DATA_2LSB 1
+#define ELF_TYPE_DYN 3
+#define ELF_MACHINE_XTENSA 94
+#define ELF_MACHINE_RISCV 243
+#define ELF_MACHINE_X86_64 62
+#define ELF_MACHINE_AARCH64 183
+
+/** What a loader needs an ELF file's header to say before it will try to load it. */
+struct ElfRequirements {
+    uint8_t elf_class; /**< ELF_CLASS_32 / ELF_CLASS_64 */
+    uint8_t data; /**< ELF_DATA_2LSB */
+    uint16_t type; /**< ELF_TYPE_DYN */
+    uint16_t machine; /**< ELF_MACHINE_XTENSA / _RISCV / _X86_64 / _AARCH64 */
+};
+
+/**
+ * Reads the first 20 bytes of @a path (e_ident, e_type, e_machine; identical offsets for
+ * ELF32 and ELF64) and checks the magic number and every field in @a requirements match.
+ * @return false if @a path can't be opened, is too short, or doesn't match
+ */
+bool elf_check_file(const char* path, const struct ElfRequirements* requirements);
+
+#ifdef __cplusplus
+}
+#endif