chore: remove retired ai moderator (#2747)

.github/workflows/moderator.yml

@@ -1,35 +0,0 @@
-name: AI Moderator
-on:
-  issues:
-    types: [opened]
-  issue_comment:
-    types: [created]
-  pull_request_review_comment:
-    types: [created]
-
-permissions: {}
-
-jobs:
-  spam-detection:
-    runs-on: ubuntu-slim
-    permissions:
-      issues: write
-      pull-requests: write
-      models: read
-      contents: read
-    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-        with:
-          persist-credentials: false
-
-      - uses: github/ai-moderator@81159c370785e295c97461ade67d7c33576e9319 # v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          spam-label: 'spam'
-          ai-label: 'ai-generated'
-          minimize-detected-comments: true
-          # Built-in prompt configuration (all enabled by default)
-          enable-spam-detection: true
-          enable-link-spam-detection: true
-          enable-ai-detection: true
-          # custom-prompt-path: '.github/prompts/my-custom.prompt.yml'  # Optional