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.

tests/engine/rom_importer_nx_saves_inbox_test.lua

@@ -59,7 +59,7 @@ package.loaded["src.import.RomImporter"] = nil
 RomImporter = require("src.import.RomImporter")
 
 local function clearSavesInbox()
-  for _, ver in ipairs({ "red", "blue", "yellow", "gold" }) do
+  for _, ver in ipairs({ "red", "blue", "yellow", "gold", "silver" }) do
     local dir = "imports/saves/" .. ver
     for _, name in ipairs(love.filesystem.getDirectoryItems(dir) or {}) do
       love.filesystem.remove(dir .. "/" .. name)
@@ -137,6 +137,8 @@ check(createdDirs["imports/saves/yellow"] == true,
   "RES-01: ensureSavesInboxDir creates imports/saves/yellow/")
 check(createdDirs["imports/saves/gold"] == true,
   "RES-01: ensureSavesInboxDir creates imports/saves/gold/")
+check(createdDirs["imports/saves/silver"] == true,
+  "RES-01: ensureSavesInboxDir creates imports/saves/silver/")
 
 -- NXSAV-02: notice/hint includes save dir + per-game imports/saves/<version>/ MTP path
 ri = freshImporter()