Add id-token: write to workflow permissions to fix OIDC error

[lgallard]

Summary:
The AWS Backup Feature Discovery workflow is failing at the "Run Claude Code Feature Discovery" step due to a missing OIDC token. The error message is:

Error message: Unable to get ACTIONS_ID_TOKEN_REQUEST_URL env variable
Did you remember to add id-token: write to your workflow permissions?

Details:
The action anthropics/claude-code-action@beta requires OIDC authentication, but the workflow permissions in .github/workflows/feature-discovery.yml (ref: bc17645ccb26b76253b5ff3121b33470c6b52f28) do not include id-token: write.

Solution:
Update the permissions section of the workflow to add:

id-token: write

Example:

permissions:
  contents: read
  issues: write
  actions: read
  id-token: write  # <-- Add this line

This will allow the job to fetch the OIDC token and proceed successfully.

Reference:

• Failing job log
• Workflow file: .github/workflows/feature-discovery.yml (ref: bc17645ccb26b76253b5ff3121b33470c6b52f28)

Impact:
Without this fix, the automated feature discovery process cannot run successfully.