fix: resolve bios case collisions

Delete duplicate lowercase variants (identical MD5) of 12 files
that prevented clean checkout on case-insensitive filesystems
(Windows, macOS).

Canonical chosen per upstream source code:
- Atari 2600 KV*.WAV: uppercase (stella2023 hardcode)
- Vectrex VEC_Minestorm.vec: lowercase (BizHawk hardcode)
- MSX MSX{,2,2EXT}.ROM: uppercase (fMSX hardcode, 6/7 platforms)
- Doom DOOM2.WAD: uppercase (matches dir convention)

Add aliases to stella2014 and clk profiles so resolution still
finds the canonical source. Correct retrodeck Vectrex casing to
match upstream. Merge Commodore/Vic-20 into VIC-20.

Add tests/test_no_case_collisions.py as a CI guard.

Closes #49

emulators/stella2014.yml

@@ -24,36 +24,43 @@ notes: |
 
 files:
   - name: kvs1.wav
+    aliases: [KVS1.WAV]
     description: "KidVid Voice Module audio tape 1 (Smurfs Save the Day)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvs2.wav
+    aliases: [KVS2.WAV]
     description: "KidVid Voice Module audio tape 2 (Smurfs Save the Day)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvs3.wav
+    aliases: [KVS3.WAV]
     description: "KidVid Voice Module audio tape 3 (Smurfs Save the Day)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvb1.wav
+    aliases: [KVB1.WAV]
     description: "KidVid Voice Module audio tape 1 (Berenstain Bears)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvb2.wav
+    aliases: [KVB2.WAV]
     description: "KidVid Voice Module audio tape 2 (Berenstain Bears)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvb3.wav
+    aliases: [KVB3.WAV]
     description: "KidVid Voice Module audio tape 3 (Berenstain Bears)"
     required: false
     category: game_data
     source_ref: "stella/src/emucore/KidVid.cxx:167,182"
   - name: kvshared.wav
+    aliases: [KVSHARED.WAV]
     description: "KidVid Voice Module shared audio samples"
     required: false
     category: game_data