feat: hle_fallback on 39 emulator profiles (266 entries)

Batch analysis of all 273 profiles to identify HLE/embedded
fallbacks. Added hle_fallback: true where the core has verified
software replacement for missing BIOS files:

- Embedded ROMs: vice (102), ep128emu (22), fuse (18), frodo (4)
- HLE BIOS: bsnes* (33 across 3 profiles), puae (9 AROS),
  noods (4), melonds* (6 FreeBIOS), flycast (3 reios)
- Open-source replacements: sameboy (8), pokemini (1), gpsp (1)
- Built-in fallbacks: np2kai (7), atari800 (6 Altirra),
  picodrive (3), quasi88 (4), gambatte (2)

Conservative: only added where notes or source code confirm HLE.
Skipped 50+ profiles where files are optional alternatives, not
HLE replaceable (neocd, opera, kronos, pcem, etc.)

emulators/melonds.yml

@@ -22,6 +22,7 @@ files:
     system: nintendo-ds
     description: "ARM9 BIOS (NDS mode)"
     required: false
+    hle_fallback: true
     size: 4096
     crc32: "0x2ab23573"
     source_ref: "src/MemConstants.h:30,37"
@@ -31,6 +32,7 @@ files:
     system: nintendo-ds
     description: "ARM7 BIOS (NDS mode)"
     required: false
+    hle_fallback: true
     size: 16384
     crc32: "0x1280f0d5"
     source_ref: "src/MemConstants.h:31,36"
@@ -40,6 +42,7 @@ files:
     system: nintendo-ds
     description: "NDS firmware image"
     required: false
+    hle_fallback: true
     source_ref: "src/frontend/qt_sdl/EmuInstance.cpp:561"
     notes: "Generated firmware used as default; native firmware needed for boot animation and wifi settings"