feat: reference pages answer every hash and field

A platform or emulator record whose value designates a collection
file carries its sha1 and is filed under the file's other hashes, so
a SHA1 paste finds the setups listing it by MD5. The data page shows
every manifest field, writes URL templates as code, states the EmuDeck
rule, the browser lookup and the empty lists. systems.json gives every
id holding files a page, Files to source splits at 100 rows with an
upload link per file, and MiSTer and BizHawk get no empty core table.

tests/test_site_r2_reference.py

@@ -208,7 +208,7 @@ class PlatformReferenceInWords(unittest.TestCase):
         systems = {"sony-playstation": {"files": [{"name": "f.bin"}]}}
         page = self._page("md5", "md5", systems)
         name = siterender.system_name("sony-playstation")
-        self.assertIn(f"| [{name}](#sony-playstation) <small>sony-playstation</small> |", page)
+        self.assertIn(f"| [{name}](#sony-playstation) <small data-pagefind-ignore>sony-playstation</small> |", page)
         heading = next(line for line in page.splitlines() if line.startswith("### ")
                        and "sony-playstation" in line)
         self.assertIn(name, heading)
@@ -335,7 +335,7 @@ class DatesAndNames(unittest.TestCase):
                          '<time datetime="2026-08-07">7 August 2026</time>')
 
     def test_data_page_title(self):
-        self.assertTrue(generate_site.generate_data_page([]).startswith("# Data and API\n"))
+        self.assertIn("\n---\n\n# Data and API\n", generate_site.generate_data_page([]))
 
 
 @unittest.skipUnless((DIST / "platforms" / "batocera" / "index.html").is_file(),