refactor: rename Aster-prefixed universal types to clean names

- AsterOrder → Order
- AsterAccountSnapshot → AccountSnapshot
- AsterAccountPosition → AccountPosition
- AsterAccountAsset → AccountAsset
- AsterDepthLevel → DepthLevel
- AsterDepth → Depth
- AsterTicker → Ticker
- AsterKline → Kline

These types are the platform-agnostic contract used by all 8 exchanges,
not Aster-specific. Renamed across 63 files.

tests/account-snapshot-validate.test.ts

@@ -1,8 +1,8 @@
 import { describe, expect, it } from "vitest";
-import type { AsterAccountSnapshot } from "../src/exchanges/types";
+import type { AccountSnapshot } from "../src/exchanges/types";
 import { validateAccountSnapshotForSymbol } from "../src/utils/strategy";
 
-function baseSnapshot(positions: AsterAccountSnapshot["positions"]): AsterAccountSnapshot {
+function baseSnapshot(positions: AccountSnapshot["positions"]): AccountSnapshot {
   return {
     canTrade: true,
     canDeposit: true,