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

docs/architecture/legacy-engine-pools.md

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+# Legacy General Pools
+
+This document summarizes the general pool system used for character selection
+and event-driven recruitment. References include `legacy/hwe/sammo/AbsGeneralPool.php`,
+`legacy/hwe/sammo/AbsFromUserPool.php`, and `legacy/hwe/sammo/GeneralPool/*`.
+
+## Core Abstractions
+
+- `AbsGeneralPool`
+  - Wraps a `Scenario\GeneralBuilder` and a raw `info` payload.
+  - Provides `getGeneralBuilder()`, `getInfo()`, and `occupyGeneralName()`.
+  - Abstract method: `pickGeneralFromPool(...)`.
+
+- `AbsFromUserPool`
+  - Implements reservation logic backed by the `select_pool` table.
+  - Reserves candidates for a user (`owner`) until `reserved_until`.
+  - On selection, clears reservation and binds `general_id`.
+
+## Pool Implementations
+
+- `GeneralPool/RandomNameGeneral`
+  - Generates random names using `GameConst::$randGen*` lists.
+  - Checks duplicate counts and appends suffixes if needed.
+  - Inserts reservation rows into `select_pool` for user selection.
+
+- `GeneralPool/SPoolUnderU30`
+  - Loads a curated pool from `GeneralPool/Pool/UnderS30.json`.
+  - Inserts rows into `select_pool` with pre-defined stats and specials.
+
+## Data Model
+
+`select_pool` table fields (observed usage):
+
+- `unique_name` (pool key)
+- `info` (JSON: stats, portrait, specials, dex, etc.)
+- `owner` (reservation user id)
+- `reserved_until` (reservation expiry)
+- `general_id` (assigned after creation)
+
+## RNG Notes
+
+Pool selection uses injected `RandUtil` to choose candidates and generate
+random names; deterministic seeding depends on caller context.