feat: document the category of every entry

Held entries carry their category and readers too, not only missing ones, so each platform page says which cores read every file it lists and where the code does it. Severity still applies to firmware gaps only.

scripts/verify.py

@@ -1192,8 +1192,8 @@ def verify_platform(
     file_status: dict[str, str] = {}
     file_required: dict[str, bool] = {}
     file_severity: dict[str, str] = {}
-    # What a missing entry is: firmware, a game's data, or a name no core
-    # the platform runs opens. Only firmware gaps carry a severity.
+    # What each entry is: firmware, a game's data, or a name no core the
+    # platform runs opens. Only firmware gaps carry a severity.
     file_category: dict[str, str] = {}
     categories = EntryCategories(config, profiles, data_dir_registry)
 
@@ -1356,13 +1356,14 @@ def verify_platform(
             prev = file_status.get(dest)
             hle = hle_index.get(file_entry.get("name", ""), False)
             sev = compute_severity(cur, required, mode, hle)
-            if cur == Status.MISSING:
-                explained = categories.explain(file_entry, destination, sys_id)
-                category = explained.pop("category")
-                result["category_evidence"] = explained
-            else:
-                category = BIOS
+            explained = categories.explain(file_entry, destination, sys_id)
+            category = explained.pop("category")
             result["category"] = category
+            result["category_evidence"] = explained
+            if cur != Status.MISSING:
+                # A held entry is firmware for the counts: its category only
+                # documents it.
+                category = BIOS
             if file_category.get(dest, category) == BIOS:
                 category = BIOS
             file_category[dest] = category