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/import/LauncherSettings.lua

@@ -573,9 +573,10 @@ end
 -- opened on the Gold tab used to offer a dozen controls that did nothing
 -- and hide the seven that the cart itself has.
 --
--- The block lives in options.lua under `gold`, which is exactly where
--- src/core/gen2/Save.lua loadOptions reads it, so an edit here is live on the
--- next boot the same way a Gen 1 edit is.  Ladders mirror
+-- The block lives in options.lua under `gold` (the historical key; Gold and
+-- Silver share it the way the Gen 1 games share the flat namespace), which is
+-- exactly where src/core/gen2/Save.lua loadOptions reads it, so an edit here
+-- is live on the next boot the same way a Gen 1 edit is.  Ladders mirror
 -- src/ui/gen2/OptionsMenu.lua's ROWS; when editing one, keep the two in sync.
 local GEN2_KEY = "gold"
 
@@ -722,7 +723,9 @@ end
 function LauncherSettings.open(hooks, version)
   local opts = SaveData.loadOptions()
   local sections
-  if version == "gold" then
+  local GameVersion = require("src.core.GameVersion")
+  if GameVersion.VERSIONS[version]
+      and GameVersion.generation(version) == 2 then
     local block = opts[GEN2_KEY]
     if type(block) ~= "table" then
       block = {}