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

docs/wiki/Warmup-Periods.md

@@ -160,7 +160,7 @@ const sma = new wickra.SMA(20);
 console.log(sma.warmupPeriod());   // -> 20
 ```
 
-(Since `wickra@0.1.5`, `warmupPeriod()` is exposed on every Node and
+(Since `wickra@0.2.0`, `warmupPeriod()` is exposed on every Node and
 WASM class — single- and multi-output — alongside `update()`, `reset()`
 and `isReady()`. Consult `bindings/node/index.d.ts` for the
 authoritative TypeScript surface.)