feat: add import/ directory for user database and config files

- Created import/db/ for custom SQL files
- Created import/conf/ for configuration overrides
- Added comprehensive README with usage examples
- Created example files for NPCs and playerbots config
- Updated import-database-files.sh to support new directory
- Maintains backward compatibility with database-import/
- Includes .gitignore to prevent accidental commits of sensitive data

import/db/examples/custom_npcs.sql

@@ -0,0 +1,18 @@
+-- Example: Add a custom NPC vendor
+-- This file demonstrates how to add a custom NPC to your world database
+
+-- Add the NPC template
+INSERT INTO `creature_template` (`entry`, `name`, `subname`, `minlevel`, `maxlevel`, `faction`, `npcflag`, `scale`, `unit_class`, `unit_flags`, `type`, `type_flags`, `InhabitType`, `RegenHealth`, `flags_extra`, `ScriptName`) 
+VALUES 
+(900000, 'Custom Vendor', 'Example NPC', 80, 80, 35, 128, 1, 1, 0, 7, 0, 3, 1, 2, '');
+
+-- Add the NPC spawn location (Stormwind Trade District)
+INSERT INTO `creature` (`guid`, `id1`, `map`, `position_x`, `position_y`, `position_z`, `orientation`, `spawntimesecs`, `MovementType`) 
+VALUES 
+(900000, 900000, 0, -8833.38, 628.628, 94.0066, 0.715585, 300, 0);
+
+-- Add some items to sell (optional)
+-- INSERT INTO `npc_vendor` (`entry`, `item`, `maxcount`, `incrtime`, `ExtendedCost`)
+-- VALUES 
+-- (900000, 2901, 0, 0, 0),  -- Mining Pick
+-- (900000, 5956, 0, 0, 0);  -- Blacksmith Hammer