feat(pipeline): add WLDS (Wowee Loading Screen) catalog

63rd open format — replaces LoadingScreens.dbc plus the
per-zone background-image tables. Defines the loading-screen
images shown when the client crosses into a new map /
instance, with optional level-bracket gating and expansion
gating (TBC art only shown if expansion installed).

When multiple screens match the player's current map + level
+ expansion, displayWeight selects randomly between them — a
zone with 3 weighted variants gets a different image roughly
proportional to weight.

4 expansion gates (Classic / TBC / WotLK / TurtleWoW),
isAnimated flag for screens with subtle animation,
isWideAspect flag for 16:9 raid intro art (vs 4:3 standard).

Cross-references with prior formats — mapId points at
WMS.map.mapId (which map triggers this loading screen);
mapId=0 is the catch-all sentinel for screens shown when
no map-specific screen matches.

CLI: --gen-lds (3 base screens — Elwynn level 1-30, Orgrimmar,
GenericFallback level 31-80 catch-all), --gen-lds-instances
(5 WotLK dungeon screens with mapId+expansion cross-refs:
Halls of Lightning/Stone, Utgarde Pinnacle, Violet Hold,
Old Kingdom), --gen-lds-raid (3 raid intro screens —
Naxxramas/Ulduar/ToC at isWideAspect=1 with weight=3),
--info-wlds, --validate-wlds with --json variants. Validator
catches id+name+texture required, expansion 0..3, level range
valid, weight=0 (in pool but never picked), and the practical
catch-all overlap warning when multiple mapId=0 screens share
overlapping level brackets (random pick becomes
non-deterministic).

Format graph: 62 → 63 binary formats. CLI flag count: 847
→ 854.

tools/editor/cli_list_formats.cpp

@@ -87,6 +87,7 @@ constexpr FormatRow kFormats[] = {
     {"WPVP", ".wpvp",  "pvp",       "honor / arena rank tables",        "PvP honor rank + arena tier catalog"},
     {"WBNK", ".wbnk",  "items",     "ItemBag.dbc + bank slots",         "Bag / bank / special slot catalog"},
     {"WRUN", ".wrun",  "spells",    "RuneCost.dbc + ChrPowerType DK",   "Death Knight rune cost catalog"},
+    {"WLDS", ".wlds",  "ui",        "LoadingScreens.dbc",               "Per-zone loading screen catalog"},
 
     // Additional pipeline catalogs without the alternating
     // gen/info/validate CLI surface (loaded by the engine