refactor: harden codebase and remove unicode artifacts

- fix urllib.parse.quote import (was urllib.request.quote)
- add operator precedence parens in generate_pack dedup check
- narrow bare except to specific types in batocera target scraper
- cache load_platform_config and build_zip_contents_index results
- add selective algorithm support to compute_hashes
- atomic write for fetch_large_file (tmp + rename)
- add response size limit to base scraper fetch
- extract build_target_cores_cache to common.py (dedup verify/pack)
- hoist _build_supplemental_index out of per-platform loop
- migrate function-attribute caches to module-level dicts
- add @abstractmethod to BaseTargetScraper.fetch_targets
- remove backward-compat re-exports from common.py
- replace em-dashes and unicode arrows with ASCII equivalents
- remove decorative section dividers and obvious comments

scripts/dedup.py

@@ -1,4 +1,4 @@
-"""Deduplicate bios/ directory — keep one canonical file per unique content.
+"""Deduplicate bios/ directory -keep one canonical file per unique content.
 
 Usage:
     python scripts/dedup.py [--dry-run] [--bios-dir bios]
@@ -11,7 +11,7 @@ Two types of deduplication:
 
 2. MAME DEVICE CLONES: Different filenames with identical content in the same
    MAME directory (e.g., bbc_m87.zip and bbc_24bbc.zip are identical ZIPs).
-   These are NOT aliases — MAME loads each by its unique name. Instead of
+   These are NOT aliases -MAME loads each by its unique name. Instead of
    deleting, we create a _mame_clones.json mapping so generate_pack.py can
    pack all names from a single canonical file.
 
@@ -94,7 +94,7 @@ def deduplicate(bios_dir: str, dry_run: bool = False) -> dict:
         if len(paths) <= 1:
             continue
 
-        # Separate by filename — same name = true duplicate, different name = clone
+        # Separate by filename -same name = true duplicate, different name = clone
         by_name: dict[str, list[str]] = defaultdict(list)
         for p in paths:
             by_name[os.path.basename(p)].append(p)
@@ -106,7 +106,7 @@ def deduplicate(bios_dir: str, dry_run: bool = False) -> dict:
                 name_paths.sort(key=path_priority)
                 true_dupes_to_remove.extend(name_paths[1:])
 
-        # Different filenames, same content — need special handling
+        # Different filenames, same content -need special handling
         unique_names = sorted(by_name.keys())
         if len(unique_names) > 1:
             # Check if these are all in MAME/Arcade dirs AND all ZIPs
@@ -133,7 +133,7 @@ def deduplicate(bios_dir: str, dry_run: bool = False) -> dict:
                             true_dupes_to_remove.append(p)
             else:
                 # Non-MAME different names (e.g., 64DD_IPL_US.n64 vs IPL_USA.n64)
-                # Keep ALL — each name may be needed by a different emulator
+                # Keep ALL -each name may be needed by a different emulator
                 # Only remove true duplicates (same name in multiple dirs)
                 pass
 
@@ -143,7 +143,7 @@ def deduplicate(bios_dir: str, dry_run: bool = False) -> dict:
         # Find the best canonical across all paths
         all_paths = [p for p in paths if p not in true_dupes_to_remove]
         if not all_paths:
-            # All copies were marked for removal — keep the best one
+            # All copies were marked for removal -keep the best one
             all_paths_sorted = sorted(paths, key=path_priority)
             all_paths = [all_paths_sorted[0]]
             true_dupes_to_remove = [p for p in paths if p != all_paths[0]]