fix: profile the beetle gba bios from its loader

emulators/beetle_gba.yml

@@ -1,14 +1,22 @@
 # Beetle GBA (Mednafen) — Game Boy Advance (libretro)
 # ref: beetle-gba-libretro/mednafen/gba, docs.libretro.com/library/beetle_gba
-# Same BIOS as mGBA/VBA-M. Optional, no HLE fallback documented.
+# Same BIOS as mGBA/VBA-M. Read only with the gba_hle core option disabled.
 emulator: Beetle GBA (Mednafen)
 type: libretro
 cores: [mednafen_gba]
 source: "https://github.com/libretro/beetle-gba-libretro"
+source_commit: "b158166237b17253188cfdbe73a8a0b9fe4b3a8c"
 systems:
   - nintendo-gba
 files:
   - name: gba_bios.bin
     system: nintendo-gba
     required: false
-    md5: a860e8c0b6d573d191e4ec7db1b1e4f6
+    hle_fallback: true
+    size: 16384
+    validation: [size]
+    source_ref: "mednafen/gba/GBA.cpp:2639-2673, mednafen/settings.cpp:81-82, libretro.cpp:223-230"
+    note: >
+      Read only when the gba_hle core option is disabled; it is enabled by
+      default and the core then uses its built-in HLE BIOS. A file of any size
+      other than 16384 bytes is ignored and the core falls back to HLE.