feat: file cards name the packs that install them

A card named only the platforms whose own list declares the file. A RetroBat user looking up scph5501.bin found every platform but RetroBat, whose pack installs it for six cores. The cards now read the install manifests and add each pack that places the file, with the destination it gives it.

scripts/cross_reference.py

@@ -341,6 +341,9 @@ class FileConsumers:
         # Where each platform puts the file in its BIOS directory.
         self.platform_destinations: dict[str, dict[str, set[str]]] = {}
         self.emulators: dict[str, set[str]] = {}
+        # Where each platform's pack installs the file, its cores' files
+        # included: the platform's own list names a fraction of them.
+        self.installed: dict[str, dict[str, set[str]]] = {}
 
     def sha1_of(self, entry: dict, dest: str = "", owner: str = "") -> str | None:
         """The collected file an entry resolves to, or None.
@@ -378,6 +381,22 @@ class FileConsumers:
                                 name, set()
                             ).add(where)
 
+    def add_manifests(self, install_dir: str | Path) -> None:
+        """Read what each install manifest places, alternatives included."""
+        for path in sorted(Path(install_dir).glob("*.json")):
+            try:
+                manifest = json.loads(path.read_text(encoding="utf-8"))
+            except (OSError, json.JSONDecodeError) as exc:
+                print(f"WARNING: {path}: {exc}", file=sys.stderr)
+                continue
+            platform = str(manifest.get("platform") or path.stem)
+            for entry in manifest.get("files") or []:
+                for sha1 in {entry.get("sha1"), *(
+                    alt.get("sha1") for alt in entry.get("alternatives") or []
+                )} - {None, ""}:
+                    self.installed.setdefault(sha1, {}).setdefault(
+                        platform, set()).add(str(entry.get("dest", "")))
+
     def path_of(self, sha1: str) -> str:
         """The collection path the database records for a file."""
         return str(self._db.get("files", {}).get(sha1, {}).get("path", ""))