Update citation bibtex for publication and add cite()

[ytdHuang]

Checklist

Thank you for contributing to QuantumToolbox.jl! Please make sure you have finished the following tasks before opening the PR.

• Please read Contributing to Quantum Toolbox in Julia.
• Any code changes were done in a way that does not break public API.
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• (If necessary) the CHANGELOG.md should be updated (regarding to the code changes) and built by running: make changelog.

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Description

Since our submission of manuscript is accepted, we should go through PR #457 again and update all the corresponding citation information after the paper is published:

• Use QuantumToolbox.jl2025 instead of QuantumToolbox-jl2025 for bibtex key
• Update the citation badge
• Update CITATION.bib file
• Update Cite section in README
• Update Cite page in documentation

Furthermore, this PR introduces cite() function to align with qutip.