Feature/memory optimization config (#108)

* feat(config): optimize memory usage to prevent OOM killer

- Reduce brightness from 95 to 50 to lower power consumption
- Reduce refresh rate from 120Hz to 100Hz to reduce CPU/memory pressure
- Reduce background service workers from 3 to 1 per manager
- Change hardware mapping from adafruit-hat-pwm to adafruit-hat
- Expected memory savings: ~700MB reduction in background service usage
- Addresses SIGKILL errors caused by memory exhaustion on Raspberry Pi

Fixes: OOM killer terminating ledmatrix.service with status=9/KILL

* revert display brightness

* refactor(background-service): hardcode optimized settings and remove config blocks

- Hardcode background service to 1 worker in all managers
- Remove background_service config blocks from template
- Simplify configuration for users - no need to adjust system settings
- Memory optimization: ~700MB reduction in background service usage
- Settings: 1 worker, 30s timeout, 3 retries (hardcoded)

Files updated:
- src/base_classes/sports.py
- src/leaderboard_manager.py
- src/odds_ticker_manager.py
- src/soccer_managers.py
- src/milb_manager.py
- config/config.template.json

This prevents OOM killer errors by reducing memory usage from
15 background threads to 5 threads total across all managers.

* remove fallback in case of background service failure

src/nba_managers.py

@@ -76,10 +76,6 @@ class BaseNBAManager(Basketball):
                     # Clear invalid cache
                     self.cache_manager.clear_cache(cache_key)
         
-        # If background service is disabled, fall back to synchronous fetch
-        if not self.background_enabled or not self.background_service:
-            return self._fetch_nba_api_data_sync(use_cache)
-        
         # Start background fetch
         self.logger.info(f"Starting background fetch for {season_year} season schedule...")
         
@@ -123,30 +119,6 @@ class BaseNBAManager(Basketball):
             return partial_data
         
         return None
-    
-    def _fetch_nba_api_data_sync(self, use_cache: bool = True) -> Optional[Dict]:
-        """
-        Synchronous fallback for fetching NFL data when background service is disabled.
-        """
-        now = datetime.now(pytz.utc)
-        current_year = now.year
-        cache_key = f"nba_schedule_{current_year}"
-
-        self.logger.info(f"Fetching full {current_year} season schedule from ESPN API (sync mode)...")
-        try:
-            response = self.session.get(ESPN_NBA_SCOREBOARD_URL, params={"dates": current_year, "limit":1000}, headers=self.headers, timeout=15)
-            response.raise_for_status()
-            data = response.json()
-            events = data.get('events', [])
-            
-            if use_cache:
-                self.cache_manager.set(cache_key, events)
-            
-            self.logger.info(f"Successfully fetched {len(events)} events for the {current_year} season.")
-            return {'events': events}
-        except requests.exceptions.RequestException as e:
-            self.logger.error(f"API error fetching full schedule: {e}")
-            return None
 
     def _fetch_data(self) -> Optional[Dict]:
         """Fetch data using shared data mechanism or direct fetch for live."""