Import cartridge .sav files with verified structure, checksums and clock (Closes #44)

Savegames → Import backup now reads an English Crystal .sav (from an
emulator, a cartridge dump or the 3DS Virtual Console's sav.dat) and
converts it into a native save after a preview.

- world/cartridge-save.ts: picks the copy TryLoadSaveFile would load
  (check values and checksums of the main copy, else the backup), reads
  the saved WRAM block, the numbered boxes, mail backups, Hall of Fame and
  Battle Tower by PRET labels (SRAM, SAVE_BLOCK in the profile, checked by
  check:reference with the SAV constants), engine flags via EngineFlags,
  scenes via MapScenes, and the map's objects and masks.
- Clock: an emulator MBC3 footer plus the time since it was written,
  FixDays/FixTime with wStart*, mapped to the minute and weekday offsets;
  without one, the device's time and the saved wCurDay. Day countdowns
  move with the day difference.
- Refused with the reason: unported maps, the Bug-Catching Contest, a
  Battle Tower challenge, characters outside the naming screen.
- Names keep <PK>/<MN> as ᴾᴷ/ᴹᴺ (one character, one tile); trainer names
  accept the naming screen's alphabet; boxed Eggs validate; native states
  up to 256 kB load (a full PC exceeded 64 kB).
- Tests: the committed debug saves, layout offsets against the symbols,
  backup fallback, clock footers, day counters, refusals, slot session
  and the Savegames flow in Chromium and WebKit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/game/party/pokemon.ts

@@ -70,11 +70,20 @@ export function partyMonDetails(mon: PartyMon): string {
   if (mon.egg) return "";
   return `:L${mon.level} HP ${mon.hp}/${mon.stats[0]}${mon.hp ? statusName(mon.status) : " FNT"}`;
 }
-/** Characters a nickname can hold: the naming screen's letters and
- * symbols, plus the digits and apostrophes of default species names. */
-export const NICKNAME_PATTERN = /^[A-Za-z0-9 ()":;[\]?!♂♀/.,×'é-]{1,10}$/u;
+/** The naming screen's <PK> and <MN> glyphs, each one character of a name,
+ * written as two small capitals. */
+export const PK = "ᴾᴷ",
+  MN = "ᴹᴺ";
+/** One character of a name: the naming screen's letters and symbols, plus
+ * the digits and apostrophes of default species names. */
+const NAME_CHARACTER = `(?:[A-Za-z0-9 ()":;[\\]?!♂♀/.,×'é-]|${PK}|${MN})`;
+/** Characters a nickname can hold (up to ten). */
+export const NICKNAME_PATTERN = new RegExp(`^${NAME_CHARACTER}{1,10}$`, "u");
 /** The same characters, for box names (up to eight). */
-export const BOX_NAME_PATTERN = /^[A-Za-z0-9 ()":;[\]?!♂♀/.,×'é-]{1,8}$/u;
+export const BOX_NAME_PATTERN = new RegExp(`^${NAME_CHARACTER}{1,8}$`, "u");
+/** The same characters, for the player's and other trainers' names (up to
+ * seven, PLAYER_NAME_LENGTH less the terminator). */
+export const TRAINER_NAME_PATTERN = new RegExp(`^${NAME_CHARACTER}{1,7}$`, "u");
 /** BASE_HAPPINESS */
 const BASE_HAPPINESS = 70;
 const MAX_STAT_VALUE = 999;
@@ -245,7 +254,7 @@ export function validBoxFields(value: unknown): boolean {
       tuple(mon.moves, 4, 251) &&
       integer(mon.otId, 0, 0xffff) &&
       typeof mon.ot === "string" &&
-      /^[A-Za-z0-9 -]{1,7}$/.test(mon.ot) &&
+      TRAINER_NAME_PATTERN.test(mon.ot) &&
       typeof mon.nickname === "string" &&
       NICKNAME_PATTERN.test(mon.nickname) &&
       integer(mon.exp, 0, 0xffffff) &&