Add API.md to document public api

API.md

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+## API Usage
+
+### List Game Metadata
+
+Get game IDs and basic metadata for games that started within a specified time range. Results are sorted by start time and paginated.
+
+**Constraints:**
+
+- Maximum time range: 2 days
+- Maximum limit per request: 1000 games
+
+**Endpoint:**
+
+```
+GET https://api.openfront.io/public/games
+```
+
+**Query Parameters:**
+
+- `start` (required): ISO 8601 timestamp
+- `end` (required): ISO 8601 timestamp
+- `limit` (optional): Number of results (max 1000)
+- `offset` (optional): Pagination offset
+
+**Example Request:**
+
+```bash
+curl "https://api.openfront.io/public/games?start=2025-10-25T00:00:00Z&end=2025-10-26T23:59:59Z&limit=10&offset=5"
+```
+
+**Response:**
+
+```json
+[
+  {
+    "game": "ABSgwin6",
+    "start": "2025-10-25T00:00:10.526Z",
+    "end": "2025-10-25T00:19:45.187Z",
+    "type": "Singleplayer",
+    "mode": "Free For All",
+    "difficulty": "Medium"
+  },
+  ...
+]
+```
+
+The response includes a `Content-Range` header indicating pagination (e.g., `games 5-15/399`).
+
+---
+
+### Get Game Info
+
+Retrieve detailed information about a specific game.
+
+**Endpoint:**
+
+```
+GET https://api.openfront.io/public/game/:gameId
+```
+
+**Query Parameters:**
+
+- `turns` (optional): Set to `false` to exclude turn data and reduce response size
+
+**Examples:**
+
+```bash
+# Full game data
+curl "https://api.openfront.io/public/game/ABSgwin6"
+
+# Without turn data
+curl "https://api.openfront.io/public/game/ABSgwin6?turns=false"
+```
+
+**Note:** Public player IDs are stripped from game records for privacy.
+
+---
+
+### Get Player Info
+
+Retrieve information and stats for a specific player.
+
+**Endpoint:**
+
+```
+GET https://api.openfront.io/public/player/:playerId
+```
+
+**Example:**
+
+```bash
+curl "https://api.openfront.io/public/player/HabCsQYR"
+```