feat: re-profile 22 emulators, refactor validation to common.py

batch re-profiled nekop2 through pokemini. mupen64plus renamed to
mupen64plus_next. new profiles: nes, mupen64plus_next.
validation functions (_build_validation_index, check_file_validation)
consolidated in common.py — single source of truth for verify.py
and generate_pack.py. pipeline 100% consistent on all 6 platforms.

emulators/pcsx1.yml

@@ -1,8 +1,46 @@
-emulator: "pcsx1"
-type: alias
-alias_of: "pcsx_rearmed"
-profiled_date: "2026-03-18"
-core_version: "r21"
+emulator: PCSX1
+type: libretro
+core_classification: community_fork
+source: "https://github.com/libretro/pcsx1-libretro"
+upstream: "https://github.com/notaz/pcsx_rearmed"
+profiled_date: "2026-03-24"
+core_version: "r22"
 display_name: "Sony - PlayStation (PCSX1)"
-note: "This core uses the same BIOS/firmware as pcsx_rearmed. See emulators/pcsx_rearmed.yml for details."
-files: []
+cores: [pcsx1]
+systems: [sony-playstation]
+notes: >
+  Never-completed fork of PCSX-ReARMed targeting general PC hardware. Experimental, abandoned since 2018.
+  HLE BIOS built-in: if no BIOS file found, core warns and falls back to HLE automatically.
+  BIOS search order: scph1001.bin, scph5501.bin, scph7001.bin by exact filename, then scans system
+  directory for any file matching "scph*" (case-insensitive) with size == 512 KB.
+  No region detection, no hash validation. First valid BIOS found is used regardless of region.
+  .info declares scph5500/5501/5502 but code explicitly searches scph1001/5501/7001 first.
+
+files:
+  - name: "scph1001.bin"
+    description: "SCPH-1001 (v2.2 12-04-95 A)"
+    required: false
+    hle_fallback: true
+    size: 524288
+    validation: [size]
+    source_ref: "frontend/libretro.c:1229 (bios[0]), :1181 (size check)"
+
+  - name: "scph5501.bin"
+    description: "SCPH-5501 (v3.0 11-18-96 A)"
+    required: false
+    hle_fallback: true
+    size: 524288
+    validation: [size]
+    source_ref: "frontend/libretro.c:1229 (bios[1]), :1181 (size check)"
+
+  - name: "scph7001.bin"
+    description: "SCPH-7001 (v4.1 12-16-97 A)"
+    required: false
+    hle_fallback: true
+    size: 524288
+    validation: [size]
+    source_ref: "frontend/libretro.c:1229 (bios[2]), :1181 (size check)"
+
+  # Dynamic scan fallback: after the 3 named files, find_any_bios() scans the
+  # system directory for any file starting with "scph" (case-insensitive) that
+  # is exactly 512 KB. This covers scph5500.bin, scph5502.bin, scph3000.bin, etc.