feat: v0.2.0 AriaEngine 自研存储引擎

- 新增 AriaEngine: LSM-Tree 页面式存储引擎，19 个模块，~3500 行 TS
  - page/: Slotted Page 格式 (header/slot/tuple/format) + CRC32
  - buffer/: Buffer Pool (LRU 缓存 + 驱逐策略)
  - index/: LSM-Tree (MemTable 红黑树 + SSTable + Bloom Filter + Merge Iterator)
  - wal/: WAL 日志 (二进制格式) + Checkpoint 管理
  - transaction/: MVCC 版本链 + 快照隔离
  - store/: IndexedDB / Memory 双后端抽象
  - compression/: LZ4 页面压缩

- 完整持久化: Schema 自动保存、SSTable 元数据管理、WAL 恢复
- 事务感知 CRUD: insert/update/delete 在事务中缓冲到 snapshot
- mode: 'aria' 激活自研引擎

- 新增 7 个测试文件，测试数 318 → 524，套件 20 → 27
  - aria-page.test.ts (32 tests): Page 格式单元测试
  - aria-index.test.ts (26 tests): Bloom Filter + MemTable
  - aria-sstable.test.ts (9 tests): SSTable Builder + Reader
  - aria-buffer.test.ts (25 tests): LRU + Eviction + Buffer Pool
  - aria-wal-mvcc.test.ts (22 tests): WAL 编解码 + MVCC 事务
  - aria-compress.test.ts (11 tests): LZ4 + Merge Iterator
  - aria.test.ts (80 tests): AriaEngine 集成 + 边界测试

- Bug 修复: LRUList size 跟踪、WAL 缓冲区越界、ColumnEncoding 导入
- 全面更新 README.md + site/ 站点文件 (index/docs/demo)

dist/metona-sqlark.d.ts

@@ -3,7 +3,7 @@
  * @module constants
  */
 /** 存储模式 */
-type StorageMode = 'memory' | 'disk' | 'hybrid';
+type StorageMode = 'memory' | 'disk' | 'hybrid' | 'aria';
 /** 磁盘引擎类型 */
 type DiskEngine = 'indexeddb' | 'opfs';
 /** 字段数据类型 */
@@ -110,7 +110,7 @@ interface MetonaPlugin {
     /** 销毁 */
     destroy(): void;
 }
-declare const VERSION = "0.1.14";
+declare const VERSION = "0.2.0";
 
 /**
  * metona-sqlark Plugin — 插件系统
@@ -612,6 +612,91 @@ declare class OPFSEngine implements IStorageEngine {
     loadTableIntoMemory(tableName: string, schema: TableSchema): Promise<void>;
 }
 
+interface AriaEngineConfig {
+    /** 页面大小（默认 4096） */
+    pageSize?: number;
+    /** Buffer Pool 页面数量（默认 256） */
+    bufferPoolPages?: number;
+    /** MemTable 刷盘阈值（默认 4MB） */
+    memtableSizeThreshold?: number;
+    /** LSM 层级之间的容量倍数（默认 10） */
+    levelSizeMultiplier?: number;
+    /** Bloom Filter 每 key 位数（默认 10） */
+    bloomFilterBitsPerKey?: number;
+    /** 是否启用 WAL（默认 true） */
+    walEnabled?: boolean;
+    /** WAL 同步模式 */
+    walSyncMode?: 'full' | 'batch' | 'none';
+    /** Checkpoint 间隔（操作数，默认 1000） */
+    checkpointInterval?: number;
+    /** 是否启用页面压缩（默认 false） */
+    compression?: boolean;
+    /** 存储后端 */
+    storageBackend?: 'indexeddb' | 'opfs' | 'memory';
+}
+
+/**
+ * AriaEngine — 自研页面式存储引擎主类
+ * @module engine/aria/index
+ *
+ * 实现 IStorageEngine 接口。
+ *
+ * v0.2.1: 完整持久化
+ *   - Schema 存入 __aria_schemas
+ *   - SSTable 元数据存入 __aria_lsm_meta
+ *   - WAL 恢复包含行数据
+ *   - 启动时自动加载 Schema + SSTable
+ */
+
+declare class AriaEngine implements IStorageEngine {
+    readonly name = "aria";
+    private config;
+    private lsm;
+    private wal;
+    private checkpointManager;
+    private backend;
+    private opened;
+    private dbName;
+    private schemas;
+    private tablePKs;
+    private opCounter;
+    private currentTxnId;
+    private txnSnapshot;
+    constructor(config?: AriaEngineConfig);
+    open(dbName: string, _version: number): Promise<void>;
+    close(): Promise<void>;
+    isOpen(): boolean;
+    createTable(schema: TableSchema): Promise<void>;
+    dropTable(tableName: string): Promise<void>;
+    hasTable(tableName: string): Promise<boolean>;
+    getTableNames(): Promise<string[]>;
+    getTableSchema(tableName: string): Promise<TableSchema | null>;
+    insert(tableName: string, rows: Record<string, unknown>[]): Promise<string[]>;
+    find(tableName: string, query: QueryPlan): Promise<Record<string, unknown>[]>;
+    update(tableName: string, query: QueryPlan, updates: Record<string, unknown>): Promise<number>;
+    delete(tableName: string, query: QueryPlan): Promise<number>;
+    count(tableName: string, query?: QueryPlan): Promise<number>;
+    clear(tableName: string): Promise<void>;
+    beginTransaction(): Promise<void>;
+    commitTransaction(): Promise<void>;
+    rollbackTransaction(): Promise<void>;
+    private getAllRows;
+    private tryIndexLookup;
+    private getPK;
+    private validateRow;
+    private checkType;
+    private persistSchemas;
+    private loadSchemas;
+    private createSSTableStore;
+    private applyWALRecord;
+    private ensureOpen;
+    private ensureTable;
+    /** Get the number of WAL records stored */
+    private getWALCount;
+    /** Set the number of WAL records stored */
+    private setWALCount;
+}
+
 /**
  * metona-sqlark Hybrid Engine — 内存 + 磁盘混合存储引擎
  * @module hybrid/index
@@ -797,4 +882,4 @@ declare global {
 
 declare const MeSqlark: typeof MetonaSqlark;
 
-export { ColumnDef, DatabaseConfig, DeleteStatement, DiskEngine, FieldType, HybridEngine, IStorageEngine, IndexedDBEngine, InsertStatement, MeSqlark, MemoryEngine, MetonaSqlark, OPFSEngine, SelectStatement, Statement, StorageMode, Table, TableSchema, UpdateStatement, VERSION, api, create, api as default, parse, tokenize };
+export { AriaEngine, AriaEngineConfig, ColumnDef, DatabaseConfig, DeleteStatement, DiskEngine, FieldType, HybridEngine, IStorageEngine, IndexedDBEngine, InsertStatement, MeSqlark, MemoryEngine, MetonaSqlark, OPFSEngine, SelectStatement, Statement, StorageMode, Table, TableSchema, UpdateStatement, VERSION, api, create, api as default, parse, tokenize };