fix: settle the round 4 site merge

Root pages nothing produced are swept, so a table moved to a platform page no longer keeps the address its redirect needs. Data tree pages name their readers, board crumbs end on the Arcade page once, fba2012 is headed FB Alpha 2012, test profiles get no page, and the installer glance lists --declared-only and --offline. sitesources.py goes through run_cli.

scripts/siterender.py

@@ -629,6 +629,12 @@ _PROGRAM_TOPS = frozenset({"Other", "Arcade"})
 # An Arcade heading can (Namco System 246), an Other one cannot.
 _NAMELESS_TOPS = frozenset({"Other"})
 
+# A section whose folder is a short name the code reads, headed with the
+# program's name instead (bios/Arcade/fba2012 holds FB Alpha 2012's samples).
+SECTION_LABELS: dict[tuple[str, str], str] = {
+    ("Arcade", "fba2012"): "FB Alpha 2012",
+}
+
 # Every (manufacturer, console) section the system pages carry.
 _section_pairs: set[tuple[str, str]] = set()
 # Normalized id -> the console sections spelled that way.