feat: hold the site to page and index budgets

validate_site.py fails a page over 1 MB of HTML, a search index over
8.5 MB (1.7 MB gzip), a skipped heading level, a table header without
text, a script from another host and a diagram drawn at runtime. The
limits sit above what the site now measures (0.88 MB, 7.2 MB, 1.43 MB),
each with its reason, and each has a test.

wiki/tools.md

@@ -692,7 +692,7 @@ python scripts/refresh_stale.py --only platforms,targets --jobs 6
 | `find_pinned_revision.py` | Walk the upstream commits that touched a file and return the revision whose bytes match a platform's pinned md5 (`--write` saves them) |
 | `generate_readme.py` | Generate README.md and CONTRIBUTING.md from database |
 | `generate_site.py` | Generate all MkDocs site pages (this documentation) |
-| `validate_site.py` | Validate rendered metadata, headings, image alternatives, JSON-LD, local resources, links and fragments |
+| `validate_site.py` | Validate rendered metadata, heading order, image alternatives, JSON-LD, local resources, links and fragments, and the page size and search index budgets |
 | `romset_recipes.py` | Identify which emulator version an arcade archive matches, and rebuild a pinned archive from ROMs already held |
 | `scraper/romset_dat_importer.py` | Fetch and import per-set recipes from MAME `-listxml` or FBNeo DATs into `recipes/`. `--fetch` alone takes the newest MAME release, and FBNeo DATs are refreshed by git blob sha. `--fetch <revision>` reads FBNeo at that tag, branch or commit |
 | `deterministic_zip.py` | Rebuild MAME BIOS ZIPs deterministically (same ROMs = same hash) |