feat: read retrobat bios groups

emulatorLauncher 228731e0 lists ten PS2 BIOS in one group: one held file
is enough and Program.cs reports the others OPTIONAL. The scraper keeps
group and optional, verify and the pack check apply the same rule.

scripts/packverify.py

@@ -774,6 +774,14 @@ def verify_pack_against_platform(
                 baseline_groups.setdefault(expected, []).append(fe)
 
         baseline_checked = len(baseline_groups)
+        # RetroBat's group: one packed file of it is enough, as verify counts it.
+        packed_groups = {
+            (system_of[id(fe)], fe["group"])
+            for expected, declarations in baseline_groups.items()
+            if expected in zip_set or expected.lower() in zip_lower
+            for fe in declarations
+            if fe.get("group")
+        }
         exclusion_index = build_zip_contents_index(db) if db is not None else {}
         categories = EntryCategories(config, emu_profiles, data_registry)
         for expected, declarations in baseline_groups.items():
@@ -795,6 +803,12 @@ def verify_pack_against_platform(
             ):
                 baseline_excluded += 1
                 continue
+            elif all(
+                fe.get("group") and (system_of[id(fe)], fe["group"]) in packed_groups
+                for fe in declarations
+            ):
+                baseline_absent += 1
+                continue
             elif db is not None and all(
                 categories.category(fe, fe.get("destination", fe.get("name", "")),
                                     system_of[id(fe)]) != BIOS

scripts/scraper/retrobat_scraper.py

@@ -217,6 +217,9 @@ class Scraper(BaseScraper):
                 sys_name = sys_data.get("name", "") if isinstance(sys_data, dict) else ""
                 if sys_name:
                     native["native_name"] = sys_name
+                # One held file of a group is enough (Program.cs): verify reads it.
+                if bios.get("group"):
+                    native["group"] = str(bios["group"])
 
                 requirements.append(
                     BiosRequirement(
@@ -224,7 +227,7 @@ class Scraper(BaseScraper):
                         system=SYSTEM_SLUG_MAP.get(sys_key, sys_key),
                         md5=md5 or None,
                         destination=file_path,
-                        required=True,
+                        required=not bios.get("optional", False),
                         native_id=sys_key,
                         native_path=declared_path,
                         native=native,

scripts/verify.py

@@ -1424,6 +1424,25 @@ def verify_platform(
             ):
                 file_severity[dest] = sev
 
+    # RetroBat's group: one file of it held is enough, and the others are
+    # reported OPTIONAL (batocera-systems/Program.cs). None held, each stays
+    # required.
+    members: dict[tuple[str, str], list[str]] = {}
+    for sys_id, system in config.get("systems", {}).items():
+        for file_entry in system.get("files", []):
+            if file_entry.get("group"):
+                dest = _dest_key(file_entry, sys_id)
+                if dest in file_status:
+                    members.setdefault((sys_id, file_entry["group"]), []).append(dest)
+    for dests in members.values():
+        if any(file_status[d] == Status.OK for d in dests):
+            for dest in dests:
+                if file_status[dest] == Status.MISSING:
+                    file_required[dest] = False
+                    file_severity[dest] = compute_severity(Status.MISSING, False, mode)
+                    for result in results_at.get(dest, []):
+                        result["required"] = False
+
     shipped, occupied = _builder_placement(
         packed_order, bool(config.get("case_insensitive_fs", False))
     )