chore: add ignore-regex to .codespellrc for improved spell checking

[futomaru]

Summary

• add an ignore-regex to skip camelCase identifiers in codespell
• reduce false positives from identifiers (e.g., spOffs, prevEnd)

Testing

• codespell (CI-equivalent run); false positives reduced by 4

References

• Refs Update codespell configuration to reduce false positives #1108

[linux-foundation-easycla]

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• ✅ login: futomaru / name: futomaru (8dda10e)