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/debug/SwitchDiagnostics.lua

@@ -249,10 +249,12 @@ function SwitchDiagnostics.probeAssets(version)
   end
 
   -- Shallow listing so we can see if the extract tree exists at all.
-  local roots = { "yellow", "blue", "gold", "assets", "yellow/assets/generated",
+  local roots = { "yellow", "blue", "gold", "silver", "assets",
+    "yellow/assets/generated",
     "yellow/assets/generated/sprites", "blue/assets/generated/sprites",
     "gold/assets/generated", "gold/assets/generated/sprites",
-    "gold/data/generated" }
+    "gold/data/generated", "silver/assets/generated",
+    "silver/data/generated" }
   for _, dir in ipairs(roots) do
     local info = filesystem.getInfo(dir)
     if info and info.type == "directory" and filesystem.getDirectoryItems then