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.

scripts/build.sh

@@ -71,6 +71,7 @@ rm -f "$LOVE_FILE"
   main.lua conf.lua src data assets tools/save-editor \
   tools/rom_manifest.json tools/rom_manifest_blue.json \
   tools/rom_manifest_yellow.json tools/rom_manifest_gold.json \
+  tools/rom_manifest_silver.json \
   -x '*.DS_Store' 'data/generated/*' 'assets/generated/*')
 # Materialize the listing once and grep the file: piping unzip straight into
 # grep -q under `set -o pipefail` SIGPIPEs unzip when grep exits early on a
@@ -90,7 +91,8 @@ for required in tools/save-editor/App.lua tools/save-editor/Kit.lua \
                 tools/save-editor/panels/Party.lua \
                 src/ui/kit/Kit.lua \
                 tools/rom_manifest.json tools/rom_manifest_blue.json \
-                tools/rom_manifest_yellow.json tools/rom_manifest_gold.json; do
+                tools/rom_manifest_yellow.json tools/rom_manifest_gold.json \
+                tools/rom_manifest_silver.json; do
   grep -qxF "$required" "$LOVE_LISTING" \
     || fail "game.love is missing $required"
 done