v0.2.0

Changed

• Breaking: optionstratlib 0.21 -> 0.22 (0.22.1: positive 0.8,
  expiration_date 0.5, option_type 0.5). Its types appear in ChainView's
  public library API (OptionChain, Positive, ExpirationDate,
  GraphData), so library consumers move to the same versions in the same
  step. The 0.22 facade is split into feature-gated component crates;
  ChainView enables only visualization (which brings pricing, market,
  analytics, strategies, simulation and backtest), with no I/O, async or
  Plotly packages.
• Imports follow the 0.22 paths: BasicAxisTypes from
  optionstratlib::model, the pricing methods through the OptionPricing
  trait, and ToPrimitive from rust_decimal (now a direct dependency),
  since the 0.22 prelude no longer re-exports it.
• Locally computed IV and Greeks move in the last digits: 0.22 inverts IV
  with one Newton solver to 1e-12 instead of a bisection to 1e-5 (the
  chain escape-hygiene golden moves by 0.01 vol point and about 0.001 theta).
  A premium no volatility can reproduce now reports SolverError instead
  of a bracket value.
• Lockfile: yoke-derive 0.8.3 (yanked) -> 0.8.4, so cargo audit passes.
• No change to the IronCondor result bundle: replay reads ChainView's own
  serde types and maps option styles itself, so bundles written against
  optionstratlib 0.21 still load.

Published to crates.io as chainview 0.2.0