Add arXiv Omi integration app

plugins/omi-arxiv-app/.gitignore

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+.venv/
+__pycache__/
+*.pyc

plugins/omi-arxiv-app/Procfile

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+web: uvicorn main:app --host 0.0.0.0 --port ${PORT:-8080}

plugins/omi-arxiv-app/README.md

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+# arXiv x Omi
+
+Search arXiv papers, inspect paper metadata, and find recent papers by author from Omi conversations.
+
+This is a standalone no-auth Omi app backed by the public arXiv API. It does not require environment variables, OAuth, or API keys.
+
+## Tools
+
+- `search_papers`: search arXiv by topic, title, author, category, or free-form query.
+- `get_paper_details`: fetch metadata for a specific arXiv paper ID.
+- `search_author`: find recent arXiv papers from a named author.
+
+## Local Development
+
+```bash
+python -m venv .venv
+source .venv/bin/activate
+pip install -r requirements.txt
+uvicorn main:app --reload --port 8080
+```
+
+Health check:
+
+```bash
+curl http://localhost:8080/health
+```
+
+Tool manifest:
+
+```bash
+curl http://localhost:8080/.well-known/omi-tools.json
+```
+
+Search papers:
+
+```bash
+curl -X POST http://localhost:8080/tools/search_papers \
+  -H "Content-Type: application/json" \
+  -d '{"query":"retrieval augmented generation", "limit":3}'
+```
+
+Fetch details:
+
+```bash
+curl -X POST http://localhost:8080/tools/get_paper_details \
+  -H "Content-Type: application/json" \
+  -d '{"paper_id":"2401.01234"}'
+```
+
+Search an author:
+
+```bash
+curl -X POST http://localhost:8080/tools/search_author \
+  -H "Content-Type: application/json" \
+  -d '{"author":"Yoshua Bengio", "limit":3}'
+```
+
+## Deployment
+
+The app is ready for Railway or Heroku-style deployment:
+
+- `Procfile` starts uvicorn on `$PORT`
+- `railway.toml` defines the same start command and `/health` check
+- `runtime.txt` pins Python 3.11
+
+## Notes
+
+arXiv metadata is returned from a public Atom feed. Result freshness, category labels, and abstracts depend on arXiv records.