release: bump 0.8.8 -> 0.8.9 (#285)

Maintenance release — supply-chain and CI housekeeping only. No library code or
public API changes.

### Security
- Triaged the pyo3 advisories RUSTSEC-2026-0176 / RUSTSEC-2026-0177 as not
  affecting Wickra (vulnerable APIs unreachable from the binding; fix blocked
  upstream by rust-numpy pinning pyo3 `^0.28`). Recorded in `deny.toml` and
  `osv-scanner.toml`.

### Changed
- Java binding: `central-publishing-maven-plugin` 0.5.0 → 0.10.0.
- CI GitHub Actions bumped to latest (checkout, setup-go, setup-java,
  codeql-action, taiki-e/install-action).
- Added a Maven ecosystem to Dependabot.

Version bumped across all manifests/lockfiles via `bump_version.py`; Cargo.lock
refreshed. CHANGELOG `[0.8.9]` filled. Tag/publish to follow on explicit GO.

examples/node/package-lock.json

@@ -17,7 +17,7 @@
     },
     "../../bindings/node": {
       "name": "wickra",
-      "version": "0.8.8",
+      "version": "0.8.9",
       "license": "MIT OR Apache-2.0",
       "devDependencies": {
         "@napi-rs/cli": "^2.18.0"
@@ -26,12 +26,12 @@
         "node": ">= 18"
       },
       "optionalDependencies": {
-        "wickra-darwin-arm64": "0.8.8",
-        "wickra-darwin-x64": "0.8.8",
-        "wickra-linux-arm64-gnu": "0.8.8",
-        "wickra-linux-x64-gnu": "0.8.8",
-        "wickra-win32-arm64-msvc": "0.8.8",
-        "wickra-win32-x64-msvc": "0.8.8"
+        "wickra-darwin-arm64": "0.8.9",
+        "wickra-darwin-x64": "0.8.9",
+        "wickra-linux-arm64-gnu": "0.8.9",
+        "wickra-linux-x64-gnu": "0.8.9",
+        "wickra-win32-arm64-msvc": "0.8.9",
+        "wickra-win32-x64-msvc": "0.8.9"
       }
     },
     "node_modules/wickra": {