feat: add emulator/system pack generation, validation checks, path resolution

add --emulator, --system, --standalone, --list-emulators, --list-systems
to verify.py and generate_pack.py. packs are RTU with data directories,
regional BIOS variants, and archive support.

validation: field per file (size, crc32, md5, sha1) with conflict
detection. by_path_suffix index in database.json for regional variant
resolution via dest_hint. restructure GameCube IPL to regional subdirs.

66 E2E tests, full pipeline verified.

emulators/dolphin.yml

@@ -14,6 +14,15 @@ systems: [nintendo-gamecube, nintendo-wii]
 #   Standalone: User/GC/ and User/Wii/
 #   Libretro (RetroArch): system/dolphin-emu/GC/ and system/dolphin-emu/Wii/
 
+pack_structure:
+  libretro: "dolphin-emu"
+  standalone: ""
+
+data_directories:
+  - ref: dolphin-sys
+    destination: "Sys"
+    source_ref: "Source/Core/Common/CommonPaths.h:128-141"
+
 files:
   # -- GameCube IPL (Boot ROM) --
   # Region-specific, placed in GC/<region>/IPL.bin