Pokemon Silver as a full launcher version, plus launcher mods-list and title-tempo fixes

Silver: derived import manifest (tools/make_silver_manifest.py re-resolves
the Gold manifest's symbols from pokesilver.sym), silver GameVersion row,
generation-keyed extractor routing, required-files override, edition save
stamping (a Silver playthrough no longer writes into the Gold save),
checkver-driven edition data, SILVER/KAMON/OSCAR/MAX presets, GOLD rival
default, edition credits banner, Lugia title screen (OAM layouts, bob,
trail, palettes as title.lua data keys with Gold defaults so old caches
need no re-import), packaging for every build target, docs, and tests.

Launcher: the installed-mods list is one continuous scroll (rows culled to
the viewport) instead of a pager with an inner scroll viewport; the pad
cursor's edge-scroll no longer runs it to the bottom. The game dropdown
shows just the initial and caret. Find-tab behavior unchanged.

Title tempo: a sprite-anim frame shows duration+1 ticks
(engine/sprite_anims/core.asm GetSpriteAnimFrame), which locks both
editions' 64-tick wing beat to the 64-tick sine bob; the title screens no
longer run fast and out of phase.

src/core/Game2.lua

@@ -3,7 +3,7 @@
 -- everything under src/*/gen2 reaches shared services through here.  Gen 1
 -- Game:load cannot consume a Gen 2 cache -- different generated tables, save
 -- shape and screen registry -- so main.lua's bootGame picks this owner when
--- GameVersion.isGold(), and the two never branch into each other.
+-- GameVersion.generation() == 2, and the two never branch into each other.
 --
 -- Boot: copyright → GameFreak Presents → GS intro stub → title
 -- (tilemap + Ho-Oh flap / clouds / trails) → Oak speech (Marill + shrink)
@@ -1702,7 +1702,7 @@ function Game2:hotkey(key)
     self:writeSave()
     return true
   elseif key == "f2" then
-    local loaded = Save.load("gold")
+    local loaded = Save.load()
     if loaded then self:continueGame(loaded) end
     return true
   elseif key == "1" then