Add momentum strategy with QQQ-based TQQQ/SQQQ trading

Implements MomentumIndicator (samples QQQ direction) and
MomentumStrategy (buys TQQQ on up, SQQQ on down, exits at
+1% target or 1hr timeout). Wired into Bot via index.ts.
Also fixes vitest config to exclude dist/ from test discovery.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/momentum-indicator.ts

@@ -0,0 +1,46 @@
+import { Alpaca } from "./alpaca";
+import { Indicator } from "./indicator";
+import { wait } from "./trading";
+
+export interface MomentumResult {
+    direction: 'up' | 'down';
+    priceBefore: number;
+    priceAfter: number;
+}
+
+export interface MomentumIndicatorConfig {
+    symbol: string;
+    settleDelay: number;
+    sampleDelay: number;
+}
+
+const defaultConfig: MomentumIndicatorConfig = {
+    symbol: 'QQQ',
+    settleDelay: 60_000,
+    sampleDelay: 1_000,
+};
+
+export class MomentumIndicator implements Indicator<MomentumResult> {
+    name = 'momentum-indicator';
+    private config: MomentumIndicatorConfig;
+
+    constructor(config: Partial<MomentumIndicatorConfig> = {}) {
+        this.config = { ...defaultConfig, ...config };
+    }
+
+    async evaluate(alpaca: Alpaca): Promise<MomentumResult> {
+        await wait(this.config.settleDelay);
+
+        const before = await alpaca.getLatestQuote(this.config.symbol);
+        const priceBefore = before.ap;
+
+        await wait(this.config.sampleDelay);
+
+        const after = await alpaca.getLatestQuote(this.config.symbol);
+        const priceAfter = after.ap;
+
+        const direction = priceAfter >= priceBefore ? 'up' : 'down';
+
+        return { direction, priceBefore, priceAfter };
+    }
+}