release: bump 0.7.9 -> 0.8.0 + Go module mirror (#237)

Bumps the workspace from 0.7.9 to 0.8.0 and adds the release-time mirror of the Go module to a standalone `wickra-go` repository.

## release.yml: `go-mirror` job
Adds a `go-mirror` job (independent of `github-release`, `needs: c-abi-build`) that on every `v*` tag:
- assembles the standalone Go module from `bindings/go` (single-package source + the vendored `include/wickra.h`),
- stages the six prebuilt C ABI libraries from the `c-abi-build` artifacts under `lib/<goos>_<goarch>/` (committed in the mirror, unlike the in-repo `lib/.gitignore`),
- rewrites `go.mod` to `module github.com/wickra-lib/wickra-go`,
- commits and tags the result in `wickra-lib/wickra-go` using the `WICKRA_GO_MIRROR_TOKEN` fine-grained PAT.

This makes `go get github.com/wickra-lib/wickra-go` build with no extra steps, closing the gap where the in-repo `bindings/go` module only built inside a full repository checkout. The mirror is a derived artifact, so its bot commit is intentionally unsigned.

## Version bump 0.7.9 -> 0.8.0
Patch never reaches double digits (`0.7.9` -> `0.8.0`). Touchpoints: `Cargo.toml` (+ `Cargo.lock` via build), `bindings/python/pyproject.toml`, `bindings/node/package.json` + 6 platform `npm/*/package.json` + both `package-lock.json` files, `bindings/java/pom.xml` + `examples/java/pom.xml` + Maven/Gradle snippets in `bindings/java/README.md`, and `CHANGELOG.md`. The C# `Wickra.csproj` (version set per tag) and `bindings/c` (inherits the workspace version) are intentionally untouched.

Tagging `v0.8.0` (which triggers the publish + the new mirror) stays gated on explicit confirmation.

examples/java/pom.xml

@@ -6,7 +6,7 @@
 
   <groupId>org.wickra.examples</groupId>
   <artifactId>wickra-examples</artifactId>
-  <version>0.7.9</version>
+  <version>0.8.0</version>
   <packaging>jar</packaging>
 
   <name>Wickra Java examples</name>
@@ -21,7 +21,7 @@
     <dependency>
       <groupId>org.wickra</groupId>
       <artifactId>wickra</artifactId>
-      <version>0.7.9</version>
+      <version>0.8.0</version>
     </dependency>
     <!-- Only the network examples (fetch_btcusdt) parse JSON. -->
     <dependency>