Refactor SettingsDefaultsManager: Move to shared directory and update imports

- Moved SettingsDefaultsManager from worker/settings to shared directory.
- Updated all import paths across the codebase to reflect the new location.
- Removed early-settings.ts as its functionality is now handled by SettingsDefaultsManager.
- Adjusted logger and paths to utilize SettingsDefaultsManager for configuration values.

README.md

@@ -333,16 +333,16 @@ nano ~/.claude-mem/settings.json
 curl http://localhost:37777/api/settings
 ```
 
-**Advanced: Environment Variable Overrides**
+**Settings File Format:**
 
-For advanced users, settings can be temporarily overridden using environment variables:
-
-```bash
-CLAUDE_MEM_WORKER_PORT=38000 claude
+```json
+{
+  "CLAUDE_MEM_MODEL": "claude-haiku-4-5",
+  "CLAUDE_MEM_WORKER_PORT": "37777",
+  "CLAUDE_MEM_CONTEXT_OBSERVATIONS": "50"
+}
 ```
 
-**Note**: The settings file takes priority. Environment variables only apply when a setting is not present in the file.
-
 See [Configuration Guide](https://docs.claude-mem.ai/configuration) for details.
 
 ---