문서 추가: 레거시 엔진 아키텍처에 대한 상세 설명 및 관련 정보 추가

docs/architecture/legacy-engine-server-env.md

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+# Legacy Server Environment
+
+This document captures the legacy server-level environment settings and
+utilities. References include `legacy/hwe/sammo/ServerDefaultEnv.php`,
+`legacy/hwe/sammo/ServerEnv.php`, and `legacy/hwe/sammo/ServerTool.php`.
+
+## Server Environment
+
+- `ServerDefaultEnv` holds server-wide constants (e.g.,
+  `maxGeneralsPerMinute`).
+- `ServerEnv` extends `ServerDefaultEnv` and is overridden by
+  `d_setting/ServerEnv.php` when present.
+
+## Turn Term Management
+
+`ServerTool::changeServerTerm($turnterm)` adjusts the global turn length:
+
+1. Validates that `turnterm` divides 120 minutes.
+2. Acquires the game lock (`tryLock()`), unless `ignoreLock` is set.
+3. Recomputes each general's `turntime` based on the new interval.
+4. Updates `game_env.turnterm` and `game_env.starttime`.
+5. Broadcasts a global history notice about the change.
+
+This is a direct mutation of runtime schedule and should be treated as an
+administrative operation.