feat(skills): add optional openhands skill — closes #477

Adds an optional autonomous-ai-agents skill that delegates coding tasks
to the OpenHands CLI (https://github.com/All-Hands-AI/OpenHands). Sits
alongside claude-code / codex / opencode and is the model-agnostic
option in that family — any LiteLLM-supported provider works.

This is a ground-truth rewrite of #19325 by @xzessmedia (Tim Koepsel).
The original PR's SKILL.md was drafted by the OpenHands agent itself and
hallucinated several flags that don't exist in the real CLI (\`--model\`,
\`--max-iterations\`, \`--workspace\`, \`--sandbox docker\`), pointed at
the wrong PyPI package (\`openhands-ai\`, which is the legacy V0 SDK),
and claimed native Windows support that the upstream docs explicitly
disclaim. Rather than cherry-pick and rewrite half the lines under
contributor authorship, the SKILL.md was rebuilt against a verified
install (\`uv tool install openhands --python 3.12\`) and a real
end-to-end \`--headless --json\` run against openrouter/openai/gpt-4o-mini.

Authorship credited via the \`author:\` frontmatter field and an
AUTHOR_MAP entry in scripts/release.py.

Changes:
- optional-skills/autonomous-ai-agents/openhands/SKILL.md (new)
- website/docs/user-guide/skills/optional/autonomous-ai-agents/autonomous-ai-agents-openhands.md (auto-gen)
- website/docs/reference/optional-skills-catalog.md (one new row)
- website/sidebars.ts (one new entry under Optional → Autonomous AI Agents)
- scripts/release.py (AUTHOR_MAP entry for xzessmedia)

Pitfalls documented in the SKILL came from running the tool, not from
the upstream README: LiteLLM bedrock/sagemaker stderr noise on every
invocation, banner spam (\`OPENHANDS_SUPPRESS_BANNER=1\` required),
\`--override-with-envs\` mandatory or the CLI ignores LLM_* env vars
entirely, the dashed-vs-undashed Conversation ID footgun for \`--resume\`,
LiteLLM model-slug double-prefix when going through OpenRouter.

scripts/release.py

@@ -87,6 +87,7 @@ AUTHOR_MAP = {
     "gaia@gaia.local": "jfuenmayor",
     "jiahuigu@users.noreply.github.com": "Jiahui-Gu",
     "openhands@all-hands.dev": "YLChen-007",
+    "3153586+xzessmedia@users.noreply.github.com": "xzessmedia",
     "AdamPlatin123@outlook.com": "AdamPlatin123",
     "32711803+waefrebeorn@users.noreply.github.com": "waefrebeorn",
     "32869278+dusterbloom@users.noreply.github.com": "dusterbloom",