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.

README.md

@@ -56,14 +56,16 @@ And before you say, "that's not a recomp", you're wrong. Recomp is an acronym. *
 [![Watch the latest update video](https://img.youtube.com/vi/yi7LkWQPKKM/maxresdefault.jpg)](https://youtu.be/yi7LkWQPKKM)
 
 This project does not include a ROM, emulate the Game Boy, transpile assembly,
-or download a disassembly. A canonical US Poke Red, Blue, Yellow, Gold, or
-Silver ROM is the only game content input.
+or download a disassembly. A canonical US Poke Red, Blue, Yellow, Gold,
+Silver, or Crystal ROM is the only game content input.
 
 The ROM is verified, used during import, and then released from memory. It is
 not copied into the cache. Later launches load the private generated cache and
-do not ask for the ROM again. Red, Blue, Yellow, Gold, and Silver can all be
-imported side by side. Gold and Silver are Gen 2 Phase 1 (import + launcher;
-see `docs/gold-phase1.md`): the Gen 2 engine is still under construction.
+do not ask for the ROM again. Red, Blue, Yellow, Gold, Silver, and Crystal can
+all be imported side by side. Gold, Silver, and Crystal are Gen 2 Phase 1
+(import + launcher; see `docs/gold-phase1.md`): the Gen 2 engine is still under
+construction, and Crystal is the newest of the three, so the launcher lists it
+as Crystal (Beta).
 
 ## Quick Start
 
@@ -71,14 +73,16 @@ Open the desktop app. On first boot, choose your legally obtained `.gb` /
 `.gbc` file or drop it onto the window. Import takes a few seconds and the
 game starts automatically.
 
-Only the canonical US Red, Blue, Yellow (1 MiB), Gold, and Silver (2 MiB)
-ROMs are accepted. The importer verifies SHA-1 before creating any game data:
+Only the canonical US Red, Blue, Yellow (1 MiB), Gold, Silver, and Crystal
+(2 MiB) ROMs are accepted. The importer verifies SHA-1 before creating any
+game data:
 
 - Red: `ea9bcae617fdf159b045185467ae58b2e4a48b9a`
 - Blue: `d7037c83e1ae5b39bde3c30787637ba1d4c48ce2`
 - Yellow: `cc7d03262ebfaf2f06772c1a480c7d9d5f4a38e1`
 - Gold: `d8b8a3600a465308c9953dfa04f0081c05bdcb94`
 - Silver: `49b163f7e57702bc939d642a18f591de55d92dae`
+- Crystal: `f4cd194bdee0d04ca4eac29e09b8e4e9d818c133`
 
 The packaged app contains neither a ROM nor pre-extracted game data. Music,
 sound effects, and cries are synthesized while the game runs from compact
@@ -219,7 +223,7 @@ entry: a desktop shortcut per game, a Steam entry, or a handheld frontend.
 
 | Option | Effect |
 | --- | --- |
-| `--game=red` | boot Red, skipping the launcher (`blue`, `yellow`, `gold` and `silver` too, or just `r` / `b` / `y` / `g` / `s`) |
+| `--game=red` | boot Red, skipping the launcher (`blue`, `yellow`, `gold`, `silver` and `crystal` too, or just `r` / `b` / `y` / `g` / `s` / `c`) |
 | `--slot=2` | load that save slot; takes a slot number or a slot id |
 | `--launcher` | open the launcher anyway, so you can edit a shortcut you already made |