feat: find a file by any hash, out of the search

Hashes, link lists, install commands, member tables and long reference
tables leave the site search: the index drops from 21.0 MB (4.88 MB
gzip) to 6.8 MB (1.33 MB gzip). Names and prose stay searchable.

files/?hash= takes a SHA1, MD5, CRC32 or SHA256 and reads one shard of
api/v1/lookup/ (about 22 KB gzip, was 675 KB) listing the collection
card, the platforms that declare the value and the profiles that check
it. files/?sha1= still opens the card, and a sha1- anchor missing from
a page is looked up there, so a card can move between pages.

Excluded blocks are section elements: the search plugin compares
elements by tag, so a div ended at the first nested div.

scripts/validate_schemas.py

@@ -446,7 +446,7 @@ def main() -> int:
             if (api_dir / name).exists()
         ] + sorted((api_dir / "platforms").glob("*.json")) + sorted(
             (api_dir / "systems").glob("*.json")
-        )
+        ) + sorted((api_dir / "lookup").glob("*.json"))
         errors.extend(
             _validate_json_files(envelope_paths, "site-api-envelope.schema.json")
         )