release: bump 0.3.1 -> 0.4.0 (#89)

Minor release. The headline user-facing change is the Node binding now
rejecting invalid indicator periods instead of silently clamping period 0
to 1 (matches Python/WASM/core); plus per-ecosystem binding READMEs and a
corrected MSRV statement in CONTRIBUTING. See CHANGELOG [0.4.0].

- Cargo.toml (workspace.package + wickra-core dep) + Cargo.lock (6 members)
- bindings/python/pyproject.toml
- bindings/node/package.json (version + 6 optionalDependencies) + package-lock.json
- bindings/node/npm/*/package.json (6 platform subpackages)
- examples/node/package-lock.json (wickra-* platform pins)
- CHANGELOG: [Unreleased] -> [0.4.0] - 2026-05-31 + compare URL

No tag pushed (release publish is a separate, user-confirmed step).

Cargo.toml

@@ -12,7 +12,7 @@ members = [
 exclude = ["fuzz"]
 
 [workspace.package]
-version = "0.3.1"
+version = "0.4.0"
 authors = ["kingchenc <support@wickra.org>"]
 edition = "2021"
 rust-version = "1.86"
@@ -24,7 +24,7 @@ keywords = ["finance", "trading", "indicators", "technical-analysis", "ta"]
 categories = ["finance", "mathematics", "science"]
 
 [workspace.dependencies]
-wickra-core = { path = "crates/wickra-core", version = "0.3.1" }
+wickra-core = { path = "crates/wickra-core", version = "0.4.0" }
 
 thiserror = "2"
 rayon = "1.10"