chore: lint and format entire codebase

Run ruff check --fix: remove unused imports (F401), fix f-strings
without placeholders (F541), remove unused variables (F841), fix
duplicate dict key (F601).

Run isort --profile black: normalize import ordering across all files.

Run ruff format: apply consistent formatting (black-compatible) to
all 58 Python files.

3 intentional E402 remain (imports after require_yaml() must execute
after yaml is available).

scripts/exporter/retrodeck_exporter.py

@@ -170,7 +170,9 @@ class Exporter(BaseExporter):
                 if native_id in manifest:
                     # Merge into existing component (multiple truth systems
                     # may map to the same native ID)
-                    existing_names = {e["filename"] for e in manifest[native_id]["bios"]}
+                    existing_names = {
+                        e["filename"] for e in manifest[native_id]["bios"]
+                    }
                     for entry in bios_entries:
                         if entry["filename"] not in existing_names:
                             manifest[native_id]["bios"].append(entry)