Add TRS-80, RX-78, Sega AI entries; refactor tools

Add many MAME/MESS BIOS entries (TRS-80 family, Bandai RX-78, Sega AI) and update docs/navigation counts (README, mkdocs). Remove empty supplemental file references from database.json and update generated timestamps and totals. Harden and refactor tooling: add MAX_RESPONSE_SIZE limited reader in base_scraper, make target scrapers an abstract base, narrow exception handling in the Batocera targets parser, and switch generate_pack.py and verify.py to use build_target_cores_cache (simplifies target config loading and error handling). verify.py also loads supplemental cross-reference names and accepts them through verify_platform. Update tests to import from updated modules (validation/truth). Misc: small bugfix for case-insensitive path conflict check.

scripts/scraper/targets/__init__.py

@@ -6,18 +6,20 @@ from __future__ import annotations
 
 import importlib
 import pkgutil
+from abc import ABC, abstractmethod
 from pathlib import Path
 
 
-class BaseTargetScraper:
+class BaseTargetScraper(ABC):
     """Base class for target scrapers."""
 
     def __init__(self, url: str = ""):
         self.url = url
 
+    @abstractmethod
     def fetch_targets(self) -> dict:
         """Fetch targets and their core lists. Returns dict matching target YAML format."""
-        raise NotImplementedError
+        ...
 
     def write_output(self, data: dict, output_path: str) -> None:
         """Write target data to YAML file."""