Fixed DLC files not saving correctly + new 16x16 region file support

[MarvelcoCode]

Description

New worlds now use 16×16 chunk region files while existing worlds (made before this commit) remain on 32×32.

Changes

Previous Behavior

All worlds used 32×32 chunk region files, which broke saved DLC's and new tut worlds

Root Cause

it always used the 32x32 system and no support for 16x16 (which is the newer system)

New Behavior

New worlds and DLC's saves use 16×16 region files. Existing saves (made before this commit) automatically stay on 32×32 to avoid corrupting them.

Fix Implementation

A marker (region_format_16) file is stamped into the save header at creation time for both empty newly created worlds and DLC's. RegionFileCache::_getRegionFile, _getChunkDataInputStream, and _getChunkDataOutputStream all check for this marker to decide between >>4 (16×16) and >>5 (32×32) region coordinates and chunk local offsets.

[MarvelcoCode]

I tested new worlds, old worlds and DLC's creation, saving and reloading and this pr is ready to merge

[codeHusky]

Is the 16x16 region format something introduced in later TUs? It would probably make more sense for us to one-way convert the worlds to 16x16 regions rather than maintaining two different world formats

[MarvelcoCode]

Is the 16x16 region format something introduced in later TUs? It would probably make more sense for us to one-way convert the worlds to 16x16 regions rather than maintaining two different world formats

yes it was, it was added in tu19ish thats why dlc are broken and new tut worlds like tu19 (curently tut world is tu 18/19 beta), i did make a convertor it broke the world, it either replaces chunks or start rendring over chunks. you cant convert a world without smth breaking cause region coordinates are way off between the two

[MarvelcoCode]

tu19 world works creds to @gabspun for testing

[codeHusky]

I'm hesitant to merge this without a full world conversion system. If that's added then we could probably move ahead with this