chore: upgrade claude-code actions from @beta to @v1

- Update action references from @beta to @v1
- Move allowed_tools to --allowedTools in claude_args
- Move mcp_config to --mcp-config in claude_args
- Move claude_env to step-level env block
- Replace timeout_minutes with GitHub native timeout-minutes

Claude-Generated-By: Claude Code (cli/claude-opus-4-5=100%)
Claude-Steers: 8
Claude-Permission-Prompts: 3
Claude-Escapes: 0

.github/workflows/claude-dedupe-issues.yml

@@ -24,12 +24,12 @@ jobs:
 
       - name: Run Claude Code slash command
         uses: anthropics/claude-code-base-action@v1
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           prompt: "/dedupe ${{ github.repository }}/issues/${{ github.event.issue.number || inputs.issue_number }}"
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
           claude_args: "--model claude-sonnet-4-5-20250929"
-          claude_env: |
-            GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Log duplicate comment event to Statsig
         if: always()