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.

src/utils/depth.ts

@@ -1,9 +1,9 @@
-import type { AsterDepth } from "../exchanges/types";
+import type { Depth } from "../exchanges/types";
 
 export type DepthImbalance = "balanced" | "buy_dominant" | "sell_dominant";
 
 export function computeDepthStats(
-  depth: AsterDepth,
+  depth: Depth,
   levels = 10,
   ratio = 3
 ): {