Implement unified Oracle mode support with auto-detection

- Unified Dockerfile with thick/thin mode auto-detection
- Single docker-compose.yaml with build arguments
- Auto-detect logic: thick mode for Oracle 10g/11g, thin mode for 12.1+
- Simplified .env configuration with clear mode selection
- Updated admin.py with FORCE_THIN_MODE and INSTANTCLIENTPATH support
- Added comprehensive documentation for both deployment modes
- Container tested successfully with thick mode for Oracle 11g compatibility

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

api/tnsnames.ora

@@ -1,4 +1,4 @@
-ROA_ROMFAST =
+ROA_CENTRAL =
   (DESCRIPTION =
     (ADDRESS_LIST =
       (ADDRESS = (PROTOCOL = TCP)(HOST = 10.0.20.122)(PORT = 1521))
@@ -6,4 +6,4 @@ ROA_ROMFAST =
     (CONNECT_DATA =
       (SID = ROA)
     )
-  )
+  )