release: bump 0.9.4 -> 0.9.5 (#329)

Maintenance release. The library API and every indicator are unchanged from
`0.9.4`; the only change that ships to users is the R package's build script.

### What's in 0.9.5
- **R package: retry the C ABI download** (`bindings/r/configure[.win]`). A freshly
  cut release can briefly 404 while assets propagate; the download is now retried
  with a ~2 min backoff instead of failing with `cannot open URL … 404`. Landed in
  #328; ships to r-universe / source installs with this release.
- The rest of #328 — CI/release-pipeline hardening (R/NuGet dependency caching,
  job timeouts 20→30 / release 45, network-install retries, wasm-publish cache) —
  is infrastructure and does not affect the published artifacts, but makes this
  release's own pipeline more robust.

Pure version-string bump on top — `bump_version.py` touched 19 files (Cargo +
Lock, pyproject, node package.json/locks + 6 platform stubs, pom + csproj +
DESCRIPTION, SECURITY, CHANGELOG `[0.9.5]` + compare URLs). `cargo fmt` clean.

Tag/publish waits for explicit GO (irreversible publish to crates.io / PyPI /
npm / NuGet / Maven / Go / r-universe).

examples/node/package-lock.json

@@ -14,7 +14,7 @@
     },
     "../../bindings/node": {
       "name": "wickra",
-      "version": "0.9.4",
+      "version": "0.9.5",
       "license": "MIT OR Apache-2.0",
       "devDependencies": {
         "@napi-rs/cli": "^2.18.0"
@@ -23,12 +23,12 @@
         "node": ">= 20"
       },
       "optionalDependencies": {
-        "wickra-darwin-arm64": "0.9.4",
-        "wickra-darwin-x64": "0.9.4",
-        "wickra-linux-arm64-gnu": "0.9.4",
-        "wickra-linux-x64-gnu": "0.9.4",
-        "wickra-win32-arm64-msvc": "0.9.4",
-        "wickra-win32-x64-msvc": "0.9.4"
+        "wickra-darwin-arm64": "0.9.5",
+        "wickra-darwin-x64": "0.9.5",
+        "wickra-linux-arm64-gnu": "0.9.5",
+        "wickra-linux-x64-gnu": "0.9.5",
+        "wickra-win32-arm64-msvc": "0.9.5",
+        "wickra-win32-x64-msvc": "0.9.5"
       }
     },
     "node_modules/wickra": {