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.

tools/modkit.py

@@ -741,7 +741,7 @@ def imported_data_dir(repo):
         return path if _generated_data_dir_ok(path) else None
 
     version = (os.environ.get("POKEPORT_VERSION") or "red").lower()
-    if version not in ("red", "blue", "yellow"):
+    if version not in ("red", "blue", "yellow", "gold", "silver"):
         version = "red"
 
     candidates = [
@@ -2393,7 +2393,8 @@ UPVALUE_CALL = re.compile(
 UPVALUE_ARGS = re.compile(
     r"""^\s*([A-Za-z_]\w*)\s*\.\s*(\w+)\s*,\s*["'](\w+)["']""")
 VERSION_MATCH = re.compile(
-    r"""[=~]=\s*["'](red|blue|yellow)["']|["'](red|blue|yellow)["']\s*[=~]=""")
+    r"""[=~]=\s*["'](red|blue|yellow|gold|silver)["']"""
+    r"""|["'](red|blue|yellow|gold|silver)["']\s*[=~]=""")
 
 
 def _line_of(body, offset):