Fix: Enable GPU acceleration for dense retrieval in search agent (rll…

…m-org#349)

* high througput search

* fix: resolve ruff linter errors

* service fallback to cpu when no gpu found

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Co-authored-by: Gitsamshi <gitsamshi@example.com>

Merge pull request rllm-org#341 from rllm-org/nightly

[v0.2.1] Merge nightly into main for rLLM v0.2.1

Update website link in README.md