feat: agnostic bios mode for filename-agnostic emulators

bios_mode: agnostic (profile) and agnostic: true (file) for
emulators that accept any valid BIOS without specific filename.
find_undeclared_files skips agnostic entries, pack extras scan
includes all matching DB files by path prefix + size criteria,
resolve_local_file has agnostic fallback with rename README.
applied to pcsx2, lrps2 (bios_mode), melonds dsi_nand (file).

scripts/verify.py

@@ -291,6 +291,10 @@ def find_undeclared_files(
         if emu_name not in relevant:
             continue
 
+        # Skip agnostic profiles entirely (filename-agnostic BIOS detection)
+        if profile.get("bios_mode") == "agnostic":
+            continue
+
         # Check if this profile is standalone: match profile name or any cores: alias
         is_standalone = emu_name in standalone_set or bool(
             standalone_set & {str(c) for c in profile.get("cores", [])}
@@ -317,6 +321,10 @@ def find_undeclared_files(
             if load_from and load_from != "system_dir":
                 continue
 
+            # Skip agnostic files (filename-agnostic, handled by agnostic scan)
+            if f.get("agnostic"):
+                continue
+
             archive = f.get("archive")
 
             # Skip files declared by the platform (by name or archive)