fix: address review feedback on auth inputs and dead base-action options

- Drop anthropic_api_key from repo workflows: only CLAUDE_CODE_OAUTH_TOKEN
  is configured as a secret, and upstream docs say to pick one auth path
- Replace the undeclared allowed_tools input in test workflows with
  claude_args --allowedTools (base-action only declares claude_args)
- Remove dead ClaudeOptions fields and INPUT_* reads that prepareRunConfig
  never consumed (mcp_config, allowed_tools, max_turns, system prompts, etc.)
- Update base-action README to document the actual inputs, with former
  dedicated inputs expressed as Claude CLI flags via claude_args

.github/workflows/test-base-action.yml

@@ -23,9 +23,8 @@ jobs:
         uses: ./base-action
         with:
           prompt: ${{ github.event.inputs.test_prompt || 'List the files in the current directory starting with "package"' }}
-          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
-          allowed_tools: "LS,Read"
+          claude_args: --allowedTools LS,Read
 
       - name: Verify inline prompt output
         run: |
@@ -81,9 +80,8 @@ jobs:
         uses: ./base-action
         with:
           prompt_file: "test-prompt.txt"
-          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
-          allowed_tools: "LS,Read"
+          claude_args: --allowedTools LS,Read
 
       - name: Verify prompt file output
         run: |