Give Gen 2 the ROM text table Gen 1 has had all along

Gold and Silver had no label-keyed string table at all.  The manifests
carried no text section, RomExtractorGen2 had no extractText, and
game.data.text was never assigned, so every call through
src/core/RomText.lua fell back to the literal written beside it.  The only
Gen 2 text the cache held was the script text in data/generated/text.lua,
keyed by bank:address for the overworld VM, which nothing can look a battle
line up in.

make_gold_manifest.py now walks data/text/'s five dialogue files for their
labels, the way make_rom_manifest.text_metadata walks pokered's, and embeds
each one's symbol.  889 labels, all of them resolving in both editions.
make_silver_manifest.py inherits the list unchanged and re-resolves the
addresses from pokesilver.sym.

RomExtractorGen2:extractText decodes them into data/generated/rom_text.lua.
The mechanism is the one extractOakSpeech already used for _OakText1-7:
resolve the label, decode from the cart, key by name.  What is new is that
the list comes from the manifest rather than being written out in Lua, so
all of data/text/ arrives instead of seven strings.

decodeGen2Text also emits the three runtime name slots it used to drop.
PlaceMoveUsersName, PlaceMoveTargetsName and PlaceEnemysName (home/text.asm)
substitute a battler's name as the line prints, so <USER>, <TARGET> and
<ENEMY> are markers, not glyphs.  Skipped as control glyphs, SubTookDamageText
decoded as "The SUBSTITUTE / took damage for" with nothing after it.

Game2:load assigns the table to self.data.text, which is what makes the
existing shared RomText helper work on Gold and Silver at all.

The new cache file is listed in the Gold override rather than bumping
CACHE_FORMAT, so caches built before this stage re-import themselves and Red,
Blue and Yellow are left alone.

tests/gen2_trade_gfx_test.lua

@@ -45,7 +45,7 @@ check(type(RomExtractorGen2.extractTrade) == "function",
   "RomExtractorGen2:extractTrade exists")
 check(extractorSource:find("results.trade = self:extractTrade()", 1, true)
   ~= nil, "and RomExtractorGen2:run calls it")
-check(extractorSource:find("local STAGE_COUNT = 26", 1, true) ~= nil,
+check(extractorSource:find("local STAGE_COUNT = 27", 1, true) ~= nil,
   "STAGE_COUNT counts the new stage, so the progress bar still ends at 1")
 
 -- pokegold.sym, bank $0a.  These are also what the cache is checked against