iOS: stop fusing mods; Pokewalker moves to its own repo

Follow-up to #452, from dogfooding the merged build on a real iPhone.

A mod fused into game.love sits in the read-only app bundle: the mod
manager's Delete can't remove it and it reappears every launch, and an
imported newer version can never fully replace it. iOS now packs no
mods, matching every other platform - mods install as .zips at runtime
with a real install/upgrade/delete lifecycle.

With nothing fusing it, mods/pokewalker moves out of this tree to its
canonical home, https://github.com/mresnick67/Gen1ReComp-Pokewalker
(already at 0.2.0 there with move learning and a paged credit dialog;
in-tree 0.1.0 was stale). docs/ios-install.md points at it. The
event:save.loaded coverage-debt entry returns to gate_meta_coverage:
its coverage came from the mod's test suite and leaves with it.

Local reproduction of the ci workflow on this branch: all tiers, mod
lint, fingerprint + meta-coverage gates green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/ios-install.md

@@ -93,9 +93,11 @@ ZIP**, then double-click the zip to unpack it.
 
 ## Optional goodies
 
-- **Pokéwalker mode** (real steps → EXP): in-game **mod manager →
-  POKEWALKER → SYNC STEPS on**, allow step access when iOS asks, and go
-  for a walk.
+- **Pokéwalker mode** (real steps → EXP): install the mod from
+  [Gen1ReComp-Pokewalker](https://github.com/mresnick67/Gen1ReComp-Pokewalker/releases)
+  (launcher → **MODS** → **Import mod .zip**), then in-game **mod
+  manager → POKEWALKER → SYNC STEPS on**, allow step access when iOS
+  asks, and go for a walk.
 - **Mods**: launcher → **MODS** tab → **Import mod .zip**.
 - **Save import/export**: buttons on each game's tab, using the normal
   iOS file picker.