feat(perf): ship client perf defaults via Default Options, add perf mods

Pack-side half of the client performance work (analysis/client-perf/).

- Add Default Options 21.1.8 (client). It copies config/defaultoptions/
  options.txt and extra/** into place only when the target is absent, so
  player changes are never clobbered. It is also client-only. packwiz
  `preserve` would also land these files in this repo's server config, which
  matters for DistantHorizons.toml [server]/[common] and SSRD's COMMON config.
- Seed provisional mid-tier defaults generated by
  analysis/client-perf/proposed-configs/build.py --ship: render distance 8,
  DH LOD radius 128 / SSAO off / 2 threads, EMF animation LOD 12, Flywheel
  TRI_LINEAR lighting, LambDynamicLights fast, SSRD 16 chunks, Sound Physics
  16 rays / 2 bounces plus per-tick caps on noisy Create sounds. All values
  are unmeasured; Phase 2 (BENCH-MATRIX.md) replaces them. ModernFix
  dynamic_resources is held back until bench block B6 passes.
- Add Sodium Extra 0.9.4, Reese's Sodium Options 2.2.4, BadOptimizations
  2.4.1 and Particle Core 0.3.3 (all client-side). Their declared ranges match
  the pins (Sodium 0.8.13, fzzy_config, Kotlin for Forge).
- Bump Puzzles Lib 21.1.62 -> 21.1.64 as a bugfix: 21.1.63 restores dropped
  access transformers. The event-cache change in 21.1.64 is Fabric-only.

.gitignore

@@ -3,3 +3,8 @@ cache/
 
 # Immersive Paintings player-upload cache (regenerated at runtime; see .packwizignore)
 immersive_paintings_cache/
+
+# Large or regenerable local artifacts
+*.tar.gz
+analysis/raw/
+analysis/client-perf/proposed-configs/out/