docs: keep classic token instructions; add recommended fine‑grained token guidance

[indcoder]

Keep the classic token instructions for users who prefer legacy tokens, and add a recommended Fine‑Grained Personal Access Token (FGA) section with least-privilege guidance (Actions=Read, Contents=Read) and PowerShell export examples.

Rationale:

• FGA reduces blast radius compared to classic repo scope.
• Provide both options so users can choose depending on their environment and org policies.

This change is documentation-only.

[Copilot]

Pull Request Overview

This PR updates the README documentation to provide both classic and fine-grained Personal Access Token (PAT) setup instructions, with a recommendation to use fine-grained tokens for better security through least-privilege principles.

• Restructures the GitHub Personal Access Token section to include both classic and fine-grained token options
• Adds detailed guidance for fine-grained tokens with minimal required permissions (Actions=Read, Contents=Read)
• Includes PowerShell environment variable export examples for fine-grained tokens

Comments suppressed due to low confidence (1)

README.md:1

• This appears to be debugging or development text that was accidentally included in the documentation. This entire line should be removed as it's not meant for end users.

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