Remove mcp_config input in favor of --mcp-config in claude_args (#485)

* Remove mcp_config input in favor of --mcp-config in claude_args

BREAKING CHANGE: The mcp_config input has been removed. Users should now use --mcp-config flag in claude_args instead.

This simplifies the action's input surface area and aligns better with the Claude Code CLI interface. Users can still add multiple MCP configurations by using multiple --mcp-config flags.

Migration:
- Before: mcp_config: '{"mcpServers": {...}}'
- After: claude_args: '--mcp-config {"mcpServers": {...}}'

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Add outer action MCP tests to workflow

- Add test-outer-action-inline-mcp job to test inline MCP config via claude_args
- Add test-outer-action-file-mcp job to test file-based MCP config via claude_args
- Keep base-action tests unchanged (they still use mcp_config parameter)
- Test that MCP tools are properly discovered and can be executed through the outer action

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Fix: Add Bun setup to outer action MCP test jobs

The test jobs for the outer action were failing because Bun wasn't installed.
Added Setup Bun step to both test-outer-action-inline-mcp and test-outer-action-file-mcp jobs.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Add id-token permission to outer action MCP test jobs

The outer action needs id-token: write permission for OIDC authentication
when using the GitHub App. Added full permissions block to both
test-outer-action-inline-mcp and test-outer-action-file-mcp jobs.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Use github_token parameter instead of id-token permission

Replace id-token: write permission with explicit github_token parameter
for both outer action MCP test jobs. This simplifies authentication by
using the provided GitHub token directly.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Use RUNNER_TEMP environment variable consistently

Changed from GitHub Actions expression syntax to environment variable
for consistency with the rest of the workflow file.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Use execution_file output from action instead of hardcoded path

Updated outer action test jobs to:
- Add step IDs (claude-inline-test, claude-file-test)
- Use the execution_file output from the action steps
- This is more reliable than hardcoding the output file path

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* tmp

* Fix MCP test assertions to match actual output format

Updated the test assertions to match the actual JSON structure:
- Tool calls are in assistant messages with type='tool_use'
- Tool results are in user messages with type='tool_result'
- The test tool returns 'Test tool response' not 'Hello from test tool'

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Make inline MCP test actually use the tool instead of just listing

Changed the inline MCP test to:
- Request that Claude uses the test tool (not just list it)
- Add --allowedTools to ensure the tool can be used
- Check that the tool was actually called and returned expected result
- Output the full JSON for debugging

This makes both tests (inline and file-based) consistent in their approach.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/entrypoints/collect-inputs.ts

@@ -17,7 +17,6 @@ export function collectActionInputsPresence(): void {
     custom_instructions: "",
     direct_prompt: "",
     override_prompt: "",
-    mcp_config: "",
     additional_permissions: "",
     claude_env: "",
     settings: "",