gitignore: scope overrides ignore to mods/, track defaultconfigs/

The previous rule 'pack/overrides/' ignored the whole directory, which
made it impossible to re-include subpaths via ! exception (git's rule).

Narrow the ignore to 'pack/overrides/mods/' -- the only path that
Build-Tweaks.ps1 actually writes -- and drop the broken whitelist
block. Other subdirs under pack/overrides/ (defaultconfigs/, etc.) now
live in git like normal source.

Adds the Waystones override that 0.16.1 attempted (spawnInVillages =
DISABLED). Bumps to 0.16.3 so launcher caches re-sync.

.gitignore

@@ -55,14 +55,9 @@ CLAUDE.md
 
 # ─── Build artifacts that get regenerated ─────────────────────────────────
 # Tweak jars rebuilt by scripts/Build-Tweaks.ps1
-pack/overrides/
+pack/overrides/mods/
 # manifest.json regenerated by scripts/Build-Pack.ps1 -- produced at scripts/
 # (default OutputPath) and copied to the deploy share by Deploy-Brass.ps1
 scripts/manifest.json
 pack/manifest.json
 
-# pack/overrides/ is build output, but defaultconfigs/ holds hand-written
-# source-of-truth configs we ship as first-run defaults (see Build-Pack.ps1).
-# Whitelist that subdir so it lives in git like other source files.
-!pack/overrides/defaultconfigs/
-!pack/overrides/defaultconfigs/**