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.

src/core/GameVersion.lua

@@ -1,6 +1,6 @@
 -- Which game this process is running: Red (the historical default), Blue,
--- Yellow, Gold, or Silver.  One source of truth for everything that differs by
--- version -- the accepted ROM hash, the import manifest, where the
+-- Yellow, Gold, Silver, or Crystal.  One source of truth for everything that
+-- differs by version -- the accepted ROM hash, the import manifest, where the
 -- extracted cache lives, and the save-file suffix -- so the importer,
 -- cache mount, SaveData, title screen and palette all agree.
 --
@@ -8,8 +8,9 @@
 -- saves are untouched, but its extracted cache lives under red/ like Blue,
 -- Yellow, and Gold (issue #899); a legacy root cache is moved into red/ once
 -- by CacheFs.migrateLegacyRedCache.  All supported versions can be imported
--- and selected side by side.  Gold and Silver are Gen 2 (see
--- docs/gold-phase1.md).
+-- and selected side by side.  Gold, Silver and Crystal are Gen 2 (see
+-- docs/gold-phase1.md); `generation` splits Gen 1 from Gen 2 and `engine`
+-- splits Gold/Silver from Crystal within Gen 2.
 --
 -- Zero requires, so it loads during love.conf and under plain Lua for tools
 -- and tests.  The active version is a process-global set once at boot from
@@ -27,6 +28,8 @@ GameVersion.VERSIONS = {
     manifest = "tools/rom_manifest.json",
     cachePrefix = "red/",   -- red/data/generated, red/assets/generated (#899)
     saveSuffix = "",        -- save.lua / save.lua.bak / save.lua.tmp
+    -- Absent reads as "gen1" (GameVersion.engine)
+    engine = "gen1",
   },
   blue = {
     id = "blue",
@@ -37,6 +40,7 @@ GameVersion.VERSIONS = {
     manifest = "tools/rom_manifest_blue.json",
     cachePrefix = "blue/",  -- blue/data/generated, blue/assets/generated
     saveSuffix = "_blue",   -- save_blue.lua / .bak / .tmp
+    engine = "gen1",
   },
   yellow = {
     id = "yellow",
@@ -47,6 +51,7 @@ GameVersion.VERSIONS = {
     manifest = "tools/rom_manifest_yellow.json",
     cachePrefix = "yellow/",  -- yellow/data/generated, yellow/assets/generated
     saveSuffix = "_yellow",   -- save_yellow.lua / .bak / .tmp
+    engine = "gen1",
   },
   -- Gen 2, Phase 1 (docs/gold-phase1.md): a 2 MiB cart, twice the size of
   -- the Gen 1 ROMs above, imported through RomExtractorGen2 instead of
@@ -64,6 +69,7 @@ GameVersion.VERSIONS = {
     saveSuffix = "_gold",     -- save_gold.lua / .bak / .tmp
     -- Absent reads as 1 (GameVersion.generation)
     generation = 2,
+    engine = "gs",
   },
   -- Gold's engine with edition-selected data; the manifest is derived from
   -- Gold's by tools/make_silver_manifest.py.
@@ -77,11 +83,34 @@ GameVersion.VERSIONS = {
     cachePrefix = "silver/",  -- silver/data/generated, silver/assets/generated
     saveSuffix = "_silver",   -- save_silver.lua / .bak / .tmp
     generation = 2,
+    engine = "gs",
+  },
+  crystal = {
+    id = "crystal",
+    label = "Crystal",
+    displayName = "Pokemon Crystal",
+    launcherName = "Crystal (Beta)",
+    sha1 = "f4cd194bdee0d04ca4eac29e09b8e4e9d818c133",
+    manifest = "tools/rom_manifest_crystal.json",
+    cachePrefix = "crystal/",  -- crystal/data/generated, crystal/assets/generated
+    saveSuffix = "_crystal",   -- save_crystal.lua / .bak / .tmp
+    generation = 2,
+    engine = "crystal",
+    fixes = {
+      -- pokegold/docs/bugs_and_glitches.md:61
+      luckyNumberBoxes = true,
+      -- pokegold/docs/bugs_and_glitches.md:88
+      surfOntoNpc = true,
+      -- pokecrystal/engine/battle/effect_commands.asm:2614
+      reflectOverflow = true,
+    },
   },
 }
 
--- Launcher column order.
-GameVersion.ORDER = { "red", "blue", "yellow", "gold", "silver" }
+local NO_FIXES = {}
+
+-- Launcher column order.  Append only (src/mods/ModProfile.lua encodes by index).
+GameVersion.ORDER = { "red", "blue", "yellow", "gold", "silver", "crystal" }
 
 GameVersion.current = "red"
 
@@ -115,6 +144,17 @@ function GameVersion.generation(id)
   return GameVersion.info(id).generation or 1
 end
 
+-- "gen1" | "gs" | "crystal": lineage within a generation.
+function GameVersion.engine(id)
+  return GameVersion.info(id).engine or "gen1"
+end
+
+-- Cart bugs a version FIXED, by fix name; an absent row reads {} and stays bugged.
+function GameVersion.fixes(id)
+  local info = GameVersion.info(id)
+  return (info and info.fixes) or NO_FIXES
+end
+
 -- Metadata for a version id, defaulting to the active one.
 function GameVersion.info(id)
   return GameVersion.VERSIONS[id or GameVersion.current]