feat: support output directories for helm template

[Ishubhammohole]

Summary

• Added withOutputDir(Path) and useReleaseName() to the template command API
• Wired both options through JNA and CGO to Helm's native install action
• Added Go and Java regression tests for manifest files and release-name nesting

Testing

• go test ./internal/helm -run '^TestTemplateFromLocal$' -count=1 — passed
• make test-go — passed
• go vet ./... — passed
• make build-native — passed
• mvn test -pl helm-java -am -Dtest=HelmTemplateTest -Dsurefire.failIfNoSpecifiedTests=false -Denforcer.skipRules=requireFilesExist — passed (16 tests)
• make build-current-platform — 106 passed, 2 skipped, 5 unrelated environment failures: two macOS native-keychain logout expectations and three signing fixtures whose resource paths contain the workspace's URL-encoded %20
• make check-authors — existing repository-wide check reports 8 unrelated files; all modified Java files include the contributor author tag

AI-assisted development was used following the repository's AGENTS.md workflow; the implementation, generated native interface alignment, diff, and reported results were reviewed before submission.

Fixes #329