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/external.cmake

@@ -305,8 +305,8 @@ set(EXTCPPSRC
 	external/morseradiotx/main.cpp
 	external/morseradiotx/ui_morse_radiotx.cpp
 
-  external/keeloqtx/main.cpp
-  external/keeloqtx/ui_keeloqtx.cpp
+  	external/keeloqtx/main.cpp
+  	external/keeloqtx/ui_keeloqtx.cpp
 	#rtty_rx
 	external/rtty_rx/main.cpp
 	external/rtty_rx/ui_rtty_rx.cpp
@@ -328,6 +328,10 @@ set(EXTCPPSRC
 	#kiss_tnc
 	external/kiss_tnc/main.cpp
 	external/kiss_tnc/ui_kiss_tnc.cpp
+
+	#fpv_detect
+	external/fpv_detect/main.cpp
+	external/fpv_detect/ui_fpv_detect.cpp
 )
 
 set(EXTAPPLIST
@@ -388,6 +392,7 @@ set(EXTAPPLIST
 	gfxeq
 	waterfall_designer
 	detector_rx
+	fpv_detect
 	spaceinv
 	blackjack
 	battleship