Phase 5: breeding with Cobbreeding, Ditto a rare Deep Dark find

Adrian (2026-10-31): add Cobbreeding without a gate; only Ditto should
be rare, in an endgame area or gated behind something else.

- Cobbreeding 2.4.1 (Modrinth only) and Cloth Config (client) in the
  pack; Cobblebase's hatchery takes Cobbreeding's eggs.
- Ditto moved from Button Isle to the Deep Dark with both of Cobblemon's
  entries (rare in slime chunks, ultra-rare elsewhere): zone_spawns.py
  pins take {"zone", "all_entries"}; Deep Dark target +1, Button Isle -1
  so no other line moved; Southwold and Frostpeak guardians pinned (they
  tie on base stats and flipped between runs).
- HMs' Trainer Ditto is made uncatchable; it still trades.
- check_deps.py skips other-side dependencies; Cobbreeding's harmless
  client-mixin log line allowlisted.
- Self-tests cobbreeding_eggs_fit_the_hatchery, trainer_ditto_cant_be_caught;
  docs, balance table, Phase 5 checklist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pack/pack.toml

@@ -6,7 +6,7 @@ pack-format = "packwiz:1.1.0"
 [index]
 file = "index.toml"
 hash-format = "sha256"
-hash = "d8359ad9c1f98c8c72503f0ce16773d7721a1a4095cfdef15ca3e985736ae6ff"
+hash = "c890308691806215f70da2c23f27010a9533c24e645a1e7cc127410e4c456453"
 
 [versions]
 minecraft = "1.21.1"