Refactor/i18n (#115)

重构i18n，现在game configs的配表，除了姓名这种外，都是统一的配表了。
对应的配表的名称和desc需要去i18n里取，但是其他配置不需要重复配置了。
这大大简化了之后新增i18n的心智负担。

docs/specs/i18n-game-configs.md

@@ -0,0 +1,59 @@
+# Game Configs I18n Refactoring Spec
+
+## Overview
+
+This document describes the refactoring of game configuration files (CSV) to support internationalization via `gettext` (.po/.mo files) instead of maintaining separate CSV files for each language.
+
+## Motivation
+
+- **Single Source of Truth**: Maintain game logic values (probabilities, stats, IDs) in one place.
+- **Separation of Concerns**: Separate data configuration from text translation.
+- **Standardization**: Use the same toolchain (gettext) for both code strings and config strings.
+
+## Architecture
+
+### 1. Data Source (`static/game_configs/`)
+- All CSV files reside in `static/game_configs/`.
+- **No language-specific folders** for CSVs (e.g., no `locales/zh-CN/game_configs`).
+- CSV Structure Changes:
+    - Added `name_id`: Translation key for the name.
+    - Added `desc_id`: Translation key for the description.
+    - `name` and `desc` columns remain as **Reference/Fallback** (usually containing Chinese).
+
+Example:
+```csv
+id,name_id,name,desc_id,desc,danger_prob
+hidden_domain_wood,HIDDEN_DOMAIN_WOOD_NAME,万木残界,HIDDEN_DOMAIN_WOOD_DESC,此乃...,0.3
+```
+
+### 2. Translation Files (`src/i18n/locales/`)
+- **`game_configs.po`**: Contains translations for config IDs.
+    - Generated/Updated via tool scanning CSVs.
+- **`messages.po`**: Contains translations for dynamic code strings (existing).
+
+### 3. Build Process
+- `tools/i18n/build_mo.py` merges `messages.po` and `game_configs.po` into a single `messages.mo` for runtime efficiency.
+- Or loads them as separate domains (Current decision: Merge for simplicity).
+
+### 4. Runtime Loading (`src/utils/df.py`)
+1. Load CSV from `static/game_configs/`.
+2. For each row:
+   - If `name_id` exists: Try `t(name_id)`. If translation found, overwrite `row['name']`.
+   - If `desc_id` exists: Try `t(desc_id)`. If translation found, overwrite `row['desc']`.
+3. Fallback: If no translation (or `t()` returns key), keep original `name`/`desc` from CSV.
+
+## Maintenance Workflow
+
+### Adding/Modifying Items
+1. Edit `static/game_configs/xxx.csv`.
+2. Add row with `id`.
+3. Fill `name`/`desc` with Chinese text (Reference).
+4. Fill `name_id`/`desc_id` (Convention: `{FILE}_{ID}_NAME`).
+5. Run extraction tool (to be created) to update `game_configs.pot` and `.po` files.
+6. Add English translation in `src/i18n/locales/en_US/LC_MESSAGES/game_configs.po`.
+7. (Optional) Run `build_mo.py` to test locally (Auto-run in build pipeline).
+
+## Tools
+
+- `tools/i18n/migrate_csv.py`: One-off script to migrate existing split CSVs to single CSV + PO.
+- `tools/i18n/extract_csv.py`: Script to scan CSVs and update POT/PO files.