Binary I/O (#5): all 12 remaining encoding/binary calls are
legitimate (zero-alloc spot-reads, random-access into game blobs).
Copy-paste handlers (#8): loadCharacterData/saveCharacterData helpers
now cover standard blob patterns.
Also upgrades saveCharacterData to send doAckSimpleFail on oversize
payloads and DB errors, and migrates handleMsgMhfSaveScenarioData
to the improved helper.
Replace the mutable global `_config.ErupeConfig` with dependency
injection across 79 files. Config is now threaded through existing
paths: `ClientContext.RealClientMode` for packet encoding, `s.server.
erupeConfig` for channel handlers, and explicit parameters for utility
functions. This removes hidden coupling, enables test parallelism
without global save/restore, and prevents low-level packages from
reaching up to the config layer.
Key changes:
- Enrich ClientContext with RealClientMode for packet files
- Add mode parameter to CryptConn, mhfitem, mhfcourse functions
- Convert handlers_commands init() to lazy sync.Once initialization
- Delete global var, init(), and helper functions from config.go
- Update all tests to pass config explicitly
