docs: standardize license to Apache-2.0 and update version references

- Change license from MIT to Apache-2.0 across all documentation to match package.json
- Update all version references from v0.3.4/v0.3.5 to v0.3.10
- Update tarball filenames from headlamp-polaris-plugin-*.tar.gz to polaris-0.3.10.tar.gz
- Update README.md license badge
- Update artifacthub-pkg.yml license field

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

artifacthub-pkg.yml

@@ -9,7 +9,7 @@ description: >-
   read-only via the Kubernetes service proxy to the Polaris dashboard.
   Requires a Role granting `get` on `services/proxy` for the
   `polaris-dashboard` service in the `polaris` namespace.
-license: MIT
+license: Apache-2.0
 homeURL: "https://github.com/privilegedescalation/headlamp-polaris-plugin"
 category: security
 keywords: