Extracts each expansion's assets as a CRC-compared overlay against a
base manifest, storing only files that differ. Auto-detects overlay mode
when a base manifest already exists. Adds --as-overlay, --full-base
flags and manifest merge for partial extractions.
Replace hardcoded WotLK protocol constants with a data-driven architecture
supporting Classic 1.12.1, TBC 2.4.3, and WotLK 3.3.5a. Each expansion
has JSON profiles for opcodes, update fields, and DBC layouts, plus C++
polymorphic packet parsers for binary format differences (movement flags,
speed fields, transport data, spline format, char enum layout).
Key components:
- ExpansionRegistry: scans Data/expansions/*/expansion.json at startup
- OpcodeTable: logical enum <-> wire values loaded from JSON
- UpdateFieldTable: field indices loaded from JSON per expansion
- DBCLayout: schema-driven DBC field lookups replacing magic numbers
- PacketParsers: WotLK/TBC/Classic parsers with correct flag positions
- Multi-manifest AssetManager: layered manifests with priority ordering
- HDPackManager: overlay texture packs with expansion compatibility
- Auth screen expansion picker replacing hardcoded version dropdown
Save/load floor cache per map (e.g., cache/wmo_floor_Azeroth.bin) instead
of a single global file. Saves current zone's cache before teleporting,
loads target zone's cache after terrain streaming completes.
