release: bump 0.5.9 -> 0.6.0 (#190)

Version bump for the **v0.6.0** release (ships the B5 Volatility & Bands batch, #189 — 423 -> 429 indicators).

Bumps version strings across Cargo workspace, pyproject, node package.json + 6 platform packages, both package-lock.json files, and Cargo.lock; CHANGELOG `[Unreleased]` -> `[0.6.0]`. No code changes.

Versioning note: patch never reaches two digits — `0.5.9` rolls to the next minor `0.6.0` (not 0.5.10).

examples/node/package-lock.json

@@ -17,7 +17,7 @@
     },
     "../../bindings/node": {
       "name": "wickra",
-      "version": "0.5.9",
+      "version": "0.6.0",
       "license": "MIT OR Apache-2.0",
       "devDependencies": {
         "@napi-rs/cli": "^2.18.0"
@@ -26,12 +26,12 @@
         "node": ">= 18"
       },
       "optionalDependencies": {
-        "wickra-darwin-arm64": "0.5.9",
-        "wickra-darwin-x64": "0.5.9",
-        "wickra-linux-arm64-gnu": "0.5.9",
-        "wickra-linux-x64-gnu": "0.5.9",
-        "wickra-win32-arm64-msvc": "0.5.9",
-        "wickra-win32-x64-msvc": "0.5.9"
+        "wickra-darwin-arm64": "0.6.0",
+        "wickra-darwin-x64": "0.6.0",
+        "wickra-linux-arm64-gnu": "0.6.0",
+        "wickra-linux-x64-gnu": "0.6.0",
+        "wickra-win32-arm64-msvc": "0.6.0",
+        "wickra-win32-x64-msvc": "0.6.0"
       }
     },
     "node_modules/wickra": {