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/flycast.yml

@@ -41,6 +41,7 @@ files:
   - name: "dc_boot.bin"
     system: sega-dreamcast
     required: false
+    hle_fallback: true
     size: 2097152  # 2 MB
     note: "Dreamcast boot ROM. HLE BIOS (reios) used as fallback."
     source_ref: "core/hw/flashrom/nvmem.cpp:287"
@@ -48,6 +49,7 @@ files:
   - name: "dc_bios.bin"
     system: sega-dreamcast
     required: false
+    hle_fallback: true
     size: 2097152
     note: "Alternate name for Dreamcast boot ROM."
     source_ref: "core/hw/flashrom/nvmem.cpp:287"
@@ -55,6 +57,7 @@ files:
   - name: "dc_flash.bin"
     system: sega-dreamcast
     required: false
+    hle_fallback: true
     size: 131072  # 128 KB
     note: "Dreamcast flash memory (settings, saves). Created if missing."
     source_ref: "core/hw/flashrom/nvmem.cpp:246"