release(0.2.0): bump version from 0.1.5 to 0.2.0

This release carries the full post-audit work — 46 new indicators
(25 → 71), an eight-family taxonomy restructure, new bindings for
RollingVWAP, the WASM streaming-update parity, the pyo3/numpy CVE
fix, the SMA/Bollinger drift bound, the O(1) LinearRegression
refactor, the UlcerIndex deque and the PSAR is_ready/reset fixes
plus a refreshed example suite and wiki. The earlier 0.1.5 number
was never published; jumping straight to 0.2.0 is the cleaner signal
for the scope of the change.

Bumped:
- Cargo.toml workspace + wickra-core workspace-dep version
- bindings/python/pyproject.toml
- bindings/node/package.json + optionalDependencies (six platform pins)
- 6 x bindings/node/npm/<target>/package.json
- Cargo.lock regenerated
- CHANGELOG.md [0.2.0] header + compare-link
- docs/wiki/Home.md published-versions table
- docs/wiki/Quickstart-{Rust,Node,WASM}.md + Warmup-Periods.md
  version-pinned narrative lines

Verified locally:
- cargo fmt/clippy/test (628 passed, 0 failed)
- cargo deny check (no suppression)
- bindings/node node --test (92/92)
- bindings/python pytest (118/118)
- import wickra reports 0.2.0 with 72 indicator classes

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-## [0.1.5] - 2026-05-23
+## [0.2.0] - 2026-05-23
 
 ### Fixed
 - `HistoricalVolatility::update` no longer substitutes a `0.0` log-return on
@@ -249,8 +249,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   optional Binance live feed.
 - Bindings for Python, Node.js, and WebAssembly.
 
-[Unreleased]: https://github.com/kingchenc/wickra/compare/v0.1.5...HEAD
-[0.1.5]: https://github.com/kingchenc/wickra/compare/v0.1.4...v0.1.5
+[Unreleased]: https://github.com/kingchenc/wickra/compare/v0.2.0...HEAD
+[0.2.0]: https://github.com/kingchenc/wickra/compare/v0.1.4...v0.2.0
 [0.1.4]: https://github.com/kingchenc/wickra/compare/v0.1.3...v0.1.4
 [0.1.3]: https://github.com/kingchenc/wickra/compare/v0.1.2...v0.1.3
 [0.1.2]: https://github.com/kingchenc/wickra/compare/v0.1.1...v0.1.2