Add Pokemon Crystal as a sixth supported version

Crystal boots from a user-supplied ROM, imports a full cache and is playable:
copyright, the Crystal intro movie, the animated title, gender select, Oak,
and out into Johto. 122 of the cart's 169 script specials are implemented.

Import and data
- tools/make_crystal_manifest.py derives the manifest by importing
  make_gold_manifest as a library, with three additive keyword seams. Gold and
  Silver still regenerate byte-identical, which is the standing requirement for
  touching that generator.
- crystal_symbol_deltas.py and crystal_movie_symbols.py carry the symbol delta:
  Crystal renames the credits mons, splits the trainer card, Pokegear and
  pack-pal blocks by gender, and replaces the intro and title outright.
- Crystal-only manifest keys: engineFlagOrder (162 flags to Gold's 93, so the
  badge block sits one higher) and unownCharmap (the main charmap parser stops
  at the first newcharmap so the two cannot contaminate each other).

Extractor
- RomExtractorGen2 becomes three-edition. Crystal corrections: PAL_MAP_BANK
  0x13, a flat PICS_FIX pic bank, audio bank 0x5e, the mapSongs id-100 hole,
  seven NPC trades, a TradeTexts stride of 8, the five Crystal tileset anim
  steps with per-row degrade, and the column-major trainer card portraits.
- New: animated front sprites (frames, bitmasks, play and idle scripts), the
  Battle Tower roster, Kris assets, Mobile System GB art, and the Crystal
  intro and title via src/import/CrystalMovie.lua.

Engine
- GameVersion gains engine(id) and fixes(id). Gold and Silver keep their
  original bugs where the bug is not hardware dependent; Crystal gets the fixes
  Crystal shipped: Lucky Number boxes 10-14, surfing onto an NPC, and the
  Reflect and Light Screen defence overflow.
- Crystal story: Suicune and Eusine, Celebi behind the GS Ball flag, the Ruins
  of Alph chambers, Buena, the Move Tutor, the Poke Seer, and the Battle Tower
  including the wInBattleTowerBattle badge-boost guard.
- Kris and the gender flag, animated fronts in battle and the summary screen,
  and mon caught data.

Verification
- Every extracted asset is pixel-compared against pret's own source PNGs.
- Gold caches are byte-identical before and after, file for file.
- New Crystal suites plus a T2 Gen 2 tier; the full suite passes.

tests/engine/mod_targets_tests.lua

@@ -27,18 +27,25 @@ end
 
 -- ------- tokens expand off GameVersion, never a literal list
 
+-- "nonesuch" is the deliberate never-a-game token for every unknown-version
+-- case below.  A real version id was used here twice ("gold", then "crystal")
+-- and both had to be swapped the day that game shipped; this one never will.
+local NO_SUCH_GAME = "nonesuch"
+
 do
   eq(table.concat(ModTargets.expand("red"), ","), "red",
     "a version id names exactly that game")
   eq(table.concat(ModTargets.expand("GEN1"), ","), "red,blue,yellow",
     "gen1 is every Gen 1 game, case-insensitive")
-  eq(table.concat(ModTargets.expand("gen2"), ","), "gold,silver",
+  eq(table.concat(ModTargets.expand("gen2"), ","), "gold,silver,crystal",
     "gen2 is every Gen 2 game")
   eq(table.concat(ModTargets.expand("silver"), ","), "silver",
     "and each of them names itself")
+  eq(table.concat(ModTargets.expand("crystal"), ","), "crystal",
+    "Crystal included, the day its VERSIONS row landed")
   eq(table.concat(ModTargets.expand("all"), ","),
     table.concat(GameVersion.ORDER, ","), "all is the launcher order itself")
-  eq(ModTargets.expand("crystal"), nil, "a game this engine has no cache for")
+  eq(ModTargets.expand(NO_SUCH_GAME), nil, "a game this engine has no cache for")
   eq(ModTargets.expand("gen9"), nil, "a generation with no games is unknown")
   eq(ModTargets.expand(7), nil, "a non-string token is not a game")
 end
@@ -48,9 +55,9 @@ do
   eq(table.concat(versions, ","), "red,gold",
     "normalize dedupes and sorts into GameVersion.ORDER")
   eq(#unknown, 0, "known tokens leave nothing unreported")
-  local _, bad = ModTargets.normalize({ "crystal", "gen1" })
+  local _, bad = ModTargets.normalize({ NO_SUCH_GAME, "gen1" })
   eq(#bad, 1, "an unknown token comes back for the caller to report")
-  eq(bad[1], "crystal", "by name")
+  eq(bad[1], NO_SUCH_GAME, "by name")
 end
 
 -- ------- the legacy reading: gen2compat only ever ADDS Gen 2
@@ -58,7 +65,7 @@ end
 do
   eq(list(mf({})), "red,blue,yellow",
     "a manifest with no games key is Gen 1, which is what it was tested as")
-  eq(list(mf({ gen2compat = true })), "red,blue,yellow,gold,silver",
+  eq(list(mf({ gen2compat = true })), "red,blue,yellow,gold,silver,crystal",
     "gen2compat keeps Gen 1 and adds Gen 2")
   eq(mf({}).gen2compat, false, "and the derived flag agrees")
   eq(mf({ gen2compat = true }).gen2compat, true, "both ways")
@@ -69,23 +76,23 @@ end
 
 do
   local gen2 = mf({ games = { "gen2" } })
-  eq(list(gen2), "gold,silver", "games can name Gen 2 alone")
+  eq(list(gen2), "gold,silver,crystal", "games can name Gen 2 alone")
   eq(gen2.gen2compat, true, "which IS the gen2compat claim the gate reads")
   local both = mf({ games = { "gen1", "gen2" } })
-  eq(list(both), "red,blue,yellow,gold,silver", "or both generations")
+  eq(list(both), "red,blue,yellow,gold,silver,crystal", "or both generations")
   local one = mf({ games = { "blue" } })
   eq(list(one), "blue", "or one single game")
   eq(one.gen2compat, false, "a Gen 1 game is not a Gen 2 claim")
-  eq(list(mf({ games = { "red" }, gen2compat = true })), "red,gold,silver",
+  eq(list(mf({ games = { "red" }, gen2compat = true })), "red,gold,silver,crystal",
     "an old gen2compat beside a new games list still adds its game")
 end
 
 do
   -- vocabulary: api 1 warns and keeps loading, api 2 refuses, exactly like
   -- every other manifest vocabulary (Manifest.violation)
-  local lenient = mf({ games = { "crystal", "red" } })
+  local lenient = mf({ games = { NO_SUCH_GAME, "red" } })
   eq(list(lenient), "red", "api 1 drops the unknown game and keeps the rest")
-  check(not pcall(mf, { api = 2, games = { "crystal" } }),
+  check(not pcall(mf, { api = 2, games = { NO_SUCH_GAME } }),
     "api 2 refuses a game it does not have")
   check(not pcall(mf, { games = "gen1" }),
     "games must be an array, not a bare string")
@@ -226,12 +233,13 @@ do
   local bad = ModProfile.decode(require("src.core.SaveSerializer").encode({
     format = "g1rmodlist", formatVersion = 1,
     profile = { name = "P", enabledByVersion = {
-      gold = { a = true }, silver = { a = true }, crystal = { a = true },
+      gold = { a = true }, silver = { a = true },
+      [NO_SUCH_GAME] = { a = true },
       red = "nope" } },
   }))
   eq(bad.enabledByVersion.gold.a, true, "a shared file's known game is kept")
   eq(bad.enabledByVersion.silver.a, true, "every one of them, not just the first")
-  eq(bad.enabledByVersion.crystal, nil, "an unknown game is dropped on read")
+  eq(bad.enabledByVersion[NO_SUCH_GAME], nil, "an unknown game is dropped on read")
   eq(bad.enabledByVersion.red, nil, "and so is a bucket that is not a table")
 end