[Feature]: add numeric comparison mode to pipeline sort step

[Astro-Han]

Description

The stepSort function in src/pipeline/steps/transform.ts:58-70 compares values using JavaScript's < / > operators directly. When API responses return numeric values as strings (which is common — e.g. Binance returns "quoteVolume": "1234567.89"), the sort uses lexicographic ordering instead of numeric ordering:

"99" > "1000"  → true  (string comparison: "9" > "1")

This causes ranking commands (top, gainers, losers, etc.) to produce incorrect results for any API that returns numbers as strings.

Current code

// transform.ts:62-68
return [...data].sort((a, b) => {
    const left = isRecord(a) ? a[key] : undefined;
    const right = isRecord(b) ? b[key] : undefined;
    const va = left ?? '';
    const vb = right ?? '';
    const cmp = va < vb ? -1 : va > vb ? 1 : 0;
    return reverse ? -cmp : cmp;
});

Suggested enhancement

Add a numeric: true option to the sort step:

- sort:
    by: quoteVolume
    order: desc
    numeric: true

Implementation: when numeric is true, convert values with Number() before comparison:

const va = numeric ? Number(left) || 0 : (left ?? '');
const vb = numeric ? Number(right) || 0 : (right ?? '');

Alternatively, auto-detect: if both values look numeric (pass isNaN(Number(val)) check), compare as numbers automatically.

Impact

Affects any YAML adapter that sorts on string-encoded numeric fields. Known example: Binance adapter's top, ticker, gainers, losers commands all sort on quoteVolume or priceChangePercent which are returned as strings.