feat: add full derivatives analytics layer (options + futures)

Implements all phases of the derivatives expansion plan:

Rust core (crates/ferro_ta_core/src/options/, src/futures/):
- BSM and Black-76 pricing (scalar + vectorized batch)
- Greeks: delta, gamma, vega, theta, rho
- Implied volatility solver (Newton + bisection fallback)
- Smile/skew metrics: ATM IV, 25-delta RR/BF, skew slope, convexity
- Chain helpers: moneyness labels, strike selection by offset or delta
- Synthetic forwards, basis, annualized basis, implied carry, carry spread
- Continuous contract stitching: weighted, back-adjusted, ratio-adjusted
- Curve analytics: calendar spreads, slope, contango/backwardation summary

PyO3 bindings (src/options/, src/futures/):
- All Rust functions registered and exposed via _ferro_ta extension

Python API (python/ferro_ta/analysis/):
- options.py: pricing, greeks, IV, smile, chain, legacy iv_rank/percentile/zscore
- futures.py: basis, carry, curve, roll, synthetic, continuous contracts
- options_strategy.py: typed strategy schemas (expiry/strike selectors, leg presets, risk controls, simulation limits)
- derivatives_payoff.py: multi-leg payoff aggregation and Greeks aggregation

Bug fix: wrap _to_f64 calls in iv_rank/iv_percentile/iv_zscore to raise
FerroTAInputError (not plain ValueError) for 2D array input.

Docs: derivatives.rst, derivatives-analytics.md, options-volatility.md,
quickstart.rst, index.rst, api/analysis.rst all updated.

Tests: 2053 pass, 12 skipped. All CI checks pass locally.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/api/analysis.rst

@@ -0,0 +1,22 @@
+Analysis Modules
+================
+
+.. automodule:: ferro_ta.analysis.options
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. automodule:: ferro_ta.analysis.futures
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. automodule:: ferro_ta.analysis.options_strategy
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. automodule:: ferro_ta.analysis.derivatives_payoff
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/api/index.rst

@@ -17,3 +17,4 @@ API Reference
    extended
    streaming
    batch
+   analysis