VS kube bridge

## VS Kube Bridge 0.1.0

This update turns `vs_kube_bridge` into the main Java-side core mod used by the pack.

The project still keeps the same mod id for compatibility:
- Mod ID: `vs_kube_bridge`

However, starting from this version, this project is no longer only a VS/KubeJS helper bridge. It is now the shared core integration mod for the pack.

## Main changes

### 1. VS / KubeJS bridge kept and expanded
- Keeps the original VS helper bridge for KubeJS
- Continues to provide pack-specific VS utility access
- Serves as the long-term base for future Java-side pack integrations

### 2. VS performance patch set
This update includes several narrow pack-specific performance patches intended to reduce expensive VS ship-aware distance checks in common gameplay paths.

Current optimization coverage includes:
- Natural spawning checks
- ChunkMap spawning-distance checks
- TargetingConditions distance checks
- Repeated mounted lookup work inside VS distance helpers
- Repeated EntityDragger server-position work
- Unloaded ship collision guard

These patches are intentionally conservative and are meant to improve performance without rewriting core VS physics.

### 3. Skyland structure placement rules merged into this project
The former standalone project responsible for Skyland structure placement rules has now been merged into `vs_kube_bridge`.

Important note:
- The active structure placement namespace is now:
  - `vs_kube_bridge:sky_island_spread`

The old standalone project is now considered integrated into this core mod and is no longer maintained separately.

### 4. Alex Caves integration merged into this project
The former standalone Alex Caves pack patch project has also been merged into `vs_kube_bridge`.

Included:
- Cave generation condition adjustment
- Runtime collision stability guard intended to reduce rare server stalls caused by collision checks touching not-yet-ready chunks

The old standalone Alex Caves patch project is now considered integrated into this core mod and is no longer maintained separately.

## Maintenance policy change

Starting from `0.1.0`, the following logic is maintained inside this project instead of separate helper mods/projects:

- VS / KubeJS integration
- VS performance patches
- Skyland structure placement rule logic
- Alex Caves pack-specific generation and stability patches

This means:
- `vs_kube_bridge` continues as the public update target
- the previously separate helper projects are no longer updated independently
- future maintenance should focus on this single core mod project

## Compatibility / update notes
- Existing pack setups using `vs_kube_bridge` can update normally
- Datapacks or structure configs should use:
  - `vs_kube_bridge:sky_island_spread`
- This version is intended for the pack's Minecraft `1.20.1` Forge environment

## Author
- `xiaobaiYWX`