feat(worldgen): v4.1 - latitude zones via density function + Lithosphere

- Replace custom LatitudeBiomeSource/BiomeBand system with
  LatitudeSignalDensityFunction + LatitudeZonePlacement (mixin-based)
- Add mandatory Lithosphere (mr_lithosphere) dependency + mixin config
- Override overworld/large_biomes noise_settings for ultra-wide terrain
- Rename remove_vanilla_ores -> z_remove_vanilla_ores (load order)
- Merge cold/hot/tempered biome tags into latitude_*_surface tags
- Rework OresCommand, OreBiomeFinderItem, ModConfigs for new system
- Remove obsolete latitude classes, tests & world preset overrides
- Bump mod_version 3.2 -> 4.1

CHANGELOG_4.1.md

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+# Custom Ore Gen — 4.1
+
+A hotfix release that removes developer-only diagnostics that could destabilise dedicated servers. **No gameplay changes** — all ore generation, the Diamond Shard tier, the Deep Dark lock and mod compatibility are identical to 4.0.
+
+---
+
+## 🐛 Bug Fixes
+
+*   **Removed world/server-corrupting code** — Three developer-only diagnostic classes were accidentally shipped in 4.0. They have been removed entirely:
+    *   `OreAuditHandler` — contained a `System.exit(0)` hard-kill that would terminate the server process, and forced chunk generation from a separate thread (a classic cause of chunk corruption).
+    *   `SpawnRelocator` — forced synchronous chunk generation on the main server thread during startup, causing deadlocks and hang.
+    *   `GenerationStabilityTest` — a GameTest utility that had no place in a release build.
+*   None of these classes were referenced by any gameplay code; removing them has **zero impact** on how the mod plays.
+
+---
+
+## 🔄 Changes
+
+*   Spawn-point behaviour reverts to vanilla (the removed `SpawnRelocator` no longer moves the spawn). Since the temperate band is 16,000 blocks wide, the vast majority of spawns still land in a balanced ore zone.
+
+---
+
+## ✅ Verification
+
+*   No `System.exit`, `Runtime.halt`, forced chunk loading (`getChunkAt`/`getChunk`), manual threads or `setBlock` calls remain anywhere in the codebase.
+*   Build and unit tests pass.
+
+---
+
+**Full build:** Minecraft 1.21.1 · NeoForge 21.1.x · Lithosphere 1.7+ (required)