feat: port GaC-hkrpg-ps to Go with SceneCastSkill camera-detach fix

- mihoyo-variant KCP in pure Go (28-byte conv+token header), UDP gateway
  with 0xFF/0x145/0x194 handshake, ms-precision KCP clock + retransmit ticker
- protobuf for 4.6.51 generated from the AstralOS StarRail.proto (4932
  messages) plus CmdID map from // CmdID: comments (2114 ids)
- sdkserver port: query_dispatch/query_gateway (Gateserver pb + base64),
  hotfix fetch, auth endpoints, SRTools freesr-data.json upload
- gameserver handlers: login flow, scene load/spawn with real monster
  entity tracking, lineup, avatar/skin, missions, tutorials (1249+855),
  bag/equip, challenge incl. StartChallenge 1787 layout + Tierce 8973 +
  peak 8948, all raw tierce replies
- SceneCastSkill camera bug fix: only real scene monsters (tracked per
  session) trigger battle; attacking props/NPCs/air replies retcode 0
  without battle_info so the camera stays locked on the character
- end-to-end smoke test simulating a client over real UDP: handshake,
  PlayerGetToken, and both SceneCastSkill paths
- reuses the Rust PS data files unchanged (freesr-data.json, persistent,
  res.json, teleports.json, challenge_data.json, mission_unlocks.json)

run_go.bat

@@ -0,0 +1,48 @@
+@echo off
+title GaC hkrpg GO Server (4.6.51)
+cd /d "%~dp0"
+
+echo ============================================================
+echo   GaC hkrpg GO - StarRail 4.6.51 Private Server (Go)
+echo   gameserver : UDP 23301 (KCP)
+echo   sdkserver  : HTTP 21000 (dispatch + login + SRTools)
+echo ============================================================
+echo.
+echo   [1] Start server (gameserver + sdkserver)
+echo   [2] Start gameserver only
+echo   [3] Start sdkserver only
+echo   [4] Build / rebuild exes (requires Go)
+echo   [5] Exit
+echo.
+set /p choice="Select: "
+
+if "%choice%"=="1" goto all
+if "%choice%"=="2" goto gs
+if "%choice%"=="3" goto sdk
+if "%choice%"=="4" goto build
+goto :eof
+
+:all
+start "GaC GO sdkserver" cmd /k sdkserver-go.exe
+start "GaC GO gameserver" cmd /k gameserver-go.exe
+echo Both servers started. Close their windows to stop them.
+pause
+goto :eof
+
+:gs
+gameserver-go.exe
+pause
+goto :eof
+
+:sdk
+sdkserver-go.exe
+pause
+goto :eof
+
+:build
+where go >nul 2>nul || set "PATH=%PATH%;C:\Program Files\Go\bin"
+go build -o gameserver-go.exe ./cmd/gameserver || (pause & goto :eof)
+go build -o sdkserver-go.exe ./cmd/sdkserver || (pause & goto :eof)
+echo Build OK.
+pause
+goto :eof