test+fix: deep generation tests + bug cleanup (licence, docs, deps)

Two cohesive passes that harden the latitude worldgen and clean up
long-standing inconsistencies.

== Bug fixes & doc alignment ==
- licence: set MIT in gradle.properties and neoforge.mods.toml
  (was "Not specified" - blocks distribution)
- OreAuditHandler: fix javadoc that referenced a non-existent system
  property; the trigger is the .oreaudit marker file. Add an explicit
  warning about the System.exit(0) and point to LatitudeGameTest as the
  non-destructive alternative
- KubeJS: remove the dead kubejs_version, the commented dependency and
  all README claims about an "automatic KubeJS script"/KubeJSIntegration
  class that no longer exists. Vanilla ore removal is now native via the
  neoforge:remove_features biome modifier
- README: refresh the technical header (1.21.1 / NeoForge 21.1.219 /
  Java 21 / v3.2, was 1.20.1/Forge/Java17/v2.1.5) and the shard-diamond
  surface note (both variants are generated, gated by shardDiamondOre)
- CLAUDE.md / CONFIG_INTEGRATION_GUIDE.md: mark the feature toggles and
  tool stats as wired (they read ModConfigs at runtime); correct the
  "hardcoded tools" claim

== Generation tests (56 unit + 6 GameTest, all green) ==
- Extract the pure geometry of LatitudeBiomeSource into LatitudeMath
  (temperature, 3-zone underground model, spawn safe zone, dual-octave
  selector index). LatitudeBiomeSource now delegates to it, so one
  source of truth drives both runtime and tests - no behaviour drift
- LatitudeMathTest (21): temperature clamp/monotonicity, zone boundaries
  without gaps, Deep Dark / cave threshold predicates, spawn-safe square
  symmetry, selector index bounds + near-uniform distribution
- BiomeBandTest (18): fromTemperature boundary cases, surface/ocean
  pool non-empty, cave biomes never in a surface pool
- ModConfigsTest (+2 guards): every ConfigHelper toggle string maps to
  a real FeatureToggleConfig field, so a typo cannot silently produce a
  dead toggle (default: return true)
- LatitudeGameTest (+4 server tests): determinism (1485 pts, 0 mismatch),
  no cave biome at surface (160k samples, 0 leak), surface continuity
  (7% transitions - large biomes), climate gradient (north=cold 100%,
  south=hot 100%, equator cold 0%)

== Build ==
- build.gradle: addModdingDependenciesTo(sourceSets.test) so pure unit
  tests can reference Minecraft types without a full game server
- neoforge.mods.toml: optional BOP/create/mekanism dependencies removed;
  declared with mandatory=false + versionRange="[0,)" they broke mod
  loading when the mods were absent ("requires X 0 or above"). Optional
  integration is already handled via data tags (required:false) and
  data-only recipes that no-op if the mod is missing
- gradlew: restore executable bit

Verification: ./gradlew test build -> BUILD SUCCESSFUL, 56/56 unit tests
            ./gradlew runGameTestServer -> 6/6 GameTests passed in 840ms

src/main/resources/META-INF/neoforge.mods.toml

@@ -1,6 +1,6 @@
 modLoader="javafml"
 loaderVersion="[1,)"
-license="Not specified"
+license="MIT"
 
 [[mods]]
 modId="${mod_id}"
@@ -23,4 +23,10 @@ description='''${mod_description}'''
 
 
 # Start of user code block dependencies configuration
+# Note: optional mods (biomesoplenty, create, mekanism) are intentionally NOT declared
+# here. Optional integration is handled via data tags with "required": false entries
+# (see data/custom_ore_gen/tags/worldgen/biome/latitude_*_surface.json) and via
+# data-only recipes (data/create, data/mekanism) which simply no-op if the mod is
+# absent. Declaring them here with mandatory=false + versionRange caused NeoForge to
+# fail loading when the mods were not installed (see commit history).
 # End of user code block dependencies configuration