⚠️ EXPERIMENTAL: Authentication and session management for Yahoo Finance.

This namespace handles cookie/crumb authentication for Yahoo's restricted
endpoints (fundamentals, options, financial statements).

WARNING: This is experimental and may break at any time. Yahoo can:
- Change authentication at any time
- Block or rate-limit requests
- Detect automated access

For production use, consider stable alternatives:
- AlphaVantage: https://www.alphavantage.co/
- Financial Modeling Prep: https://financialmodelingprep.com/
- Polygon.io: https://polygon.io/

Implementation notes:
- Uses singleton session (thread-unsafe, single-user)
- Cookies auto-refresh every hour
- MAX 1 retry on authentication failure
- Rate-limit protection via session reuse

EXPERIMENTAL: Fetch data from Yahoo Finance quoteSummary endpoint.

This namespace provides access to company data via Yahoo's authenticated
quoteSummary API. The underlying fetch-quotesummary* function accepts any
combination of quoteSummary modules, making it easy to add new data types.

Available modules (pass to fetch-quotesummary*):
- financialData            - Price targets, margins, revenue, cash flow
- defaultKeyStatistics     - P/E, market cap, beta, shares outstanding
- assetProfile             - Sector, industry, description, employees
- earningsTrend            - Analyst EPS/revenue estimates by period
- recommendationTrend      - Buy/hold/sell counts over time
- earningsHistory          - Historical EPS vs estimates
- incomeStatementHistory   - Annual/quarterly income statements
- balanceSheetHistory      - Annual/quarterly balance sheets
- cashflowStatementHistory - Annual/quarterly cash flow statements

WARNING: This is experimental and may break at any time. Yahoo can change
or block authentication without notice.

For production use, consider stable alternatives:
- AlphaVantage (free tier, good fundamentals)
- Financial Modeling Prep (comprehensive)
- Polygon.io (professional-grade)

Implementation notes:
- Returns ALL fields from Yahoo (no filtering)
- Session auto-refreshes every hour
- MAX 1 retry on authentication failure

EXPERIMENTAL: Fetch options chain data from Yahoo Finance.

This namespace provides access to options chains via Yahoo's authenticated
v7 options endpoint. Authentication is handled automatically via the shared
session in clj-yfinance.experimental.auth.

WARNING: This is experimental and may break at any time. Yahoo can change
or block authentication without notice.

For production use, consider stable alternatives:
- AlphaVantage (free tier, options data available)
- Polygon.io (professional-grade, comprehensive options)
- Tradier (options-focused API)

Implementation notes:
- Uses /v7/finance/options endpoint (different from quoteSummary)
- Without :expiration returns nearest expiry + full list of available dates
- With :expiration (epoch seconds) returns full calls/puts chain for that date
- Each contract map includes: strike, bid, ask, lastPrice, impliedVolatility,
  openInterest, volume, inTheMoney, contractSymbol, expiration, lastTradeDate
- Session auto-refreshes every hour
- MAX 1 retry on authentication failure