Add FPV DETECT external app with Auto-scan FPV Presence Receiver (#3084)

* fpv_rx external app implemented

* FPV DETECT: PR feedback and Copilot suggestions

- Rename app from 'FPV RX' to 'FPV DETECT' (menu and title)
- Add fpv_rx to EXTAPPLIST in external.cmake so app is included in build
- Set external_apps_address_end = 0xAE010000 in external_app_info.py
- Fix clang-format in ui_fpv_rx.cpp (update_visual_state block)
- Re-sample adjacent channels during candidate verification so
  neighbor_margin lock decision uses current measurements instead of
  stale channel_memory_ from scan (reduces false/missed locks)

Made-with: Cursor

* Rename fpv_rx to fpv_detect (files, dir, app id)

- Rename directory external/fpv_rx -> external/fpv_detect
- Rename ui_fpv_rx.{cpp,hpp} -> ui_fpv_detect.{cpp,hpp}
- Update external.cmake and external.ld for fpv_detect
- Namespace fpv_rx -> fpv_detect, class FpvRxView -> FpvDetectView
- Section/symbol .app_fpv_rx -> .app_fpv_detect

Made-with: Cursor

firmware/application/external/fpv_detect/main.cpp

@@ -0,0 +1,65 @@
+// Author: berkeozkir (Berke Özkır)
+
+#include "ui.hpp"
+#include "ui_fpv_detect.hpp"
+#include "ui_navigation.hpp"
+#include "external_app.hpp"
+
+namespace ui::external_app::fpv_detect {
+void initialize_app(ui::NavigationView& nav) {
+    nav.push<FpvDetectView>();
+}
+}  // namespace ui::external_app::fpv_detect
+
+extern "C" {
+
+__attribute__((section(".external_app.app_fpv_detect.application_information"), used)) application_information_t _application_information_fpv_detect = {
+    /*.memory_location = */ (uint8_t*)0x00000000,
+    /*.externalAppEntry = */ ui::external_app::fpv_detect::initialize_app,
+    /*.header_version = */ CURRENT_HEADER_VERSION,
+    /*.app_version = */ VERSION_MD5,
+
+    /*.app_name = */ "FPV DETECT",
+    /*.bitmap_data = */
+    {
+        0x00,
+        0x00,
+        0xC0,
+        0x03,
+        0x20,
+        0x04,
+        0x10,
+        0x08,
+        0x48,
+        0x12,
+        0xA4,
+        0x25,
+        0x54,
+        0x2A,
+        0xA8,
+        0x15,
+        0x54,
+        0x2A,
+        0xA4,
+        0x25,
+        0x48,
+        0x12,
+        0x10,
+        0x08,
+        0x20,
+        0x04,
+        0xC0,
+        0x03,
+        0x00,
+        0x00,
+        0x00,
+        0x00,
+    },
+    /*.icon_color = */ ui::Color::cyan().v,
+    /*.menu_location = */ app_location_t::RX,
+    /*.desired_menu_position = */ -1,
+
+    /*.m4_app_tag = portapack::spi_flash::image_tag_wfm_audio */ {'P', 'W', 'F', 'M'},
+    /*.m4_app_offset = */ 0x00000000,
+};
+}