Failed MCP servers from coding agent settings should not break unrelated agentic workflows

## Problem

An agentic workflow (`daily-team-status`) hard-failed because an MCP server defined in the repo's `.mcp.json` failed to launch inside the gh-aw sandbox — even though the workflow never requested that server.

**Failed run:** https://github.com/RealPage/task-management/actions/runs/23258101607

## Root Cause

The repo had a `.mcp.json` at the root configuring a SonarQube MCP server that launches via Docker. The coding agent auto-discovers `.mcp.json` and attempts to start all servers defined in it. Inside the gh-aw chroot sandbox:

1. **Docker is unavailable** — the sandbox is a chroot jail, not a full Docker environment. The Docker socket is not mounted, so the `docker run` command fails immediately.
2. **The image is not pre-pulled** — the `Download container images` step only pulls gh-aw infrastructure images, not project-specific MCP images.
3. **Docker Hub is not on the firewall allowlist** — even if Docker were available, `registry-1.docker.io` / `production.cloudflare.docker.com` are not in `--allow-domains`, so image pulls would be blocked.

The failure happens at the Docker binary/socket level before any network call — confirmed by firewall logs showing 0 blocked requests and only 2 unique domains (`api.anthropic.com`, `raw.githubusercontent.com`).

## Error

```
ERR_API: MCP server(s) failed to launch: sonarqube
```

This error annotation marks the entire job as `failure`, despite the agent completing successfully and producing all expected outputs.

## Workaround

We removed `.mcp.json` from version control and added it to `.gitignore` (https://github.com/RealPage/task-management/pull/1129). Developers recreate it locally. This works but sacrifices the "just works on clone" experience for project-specific MCP servers.

## Request

MCP server launch failures should **not** be fatal for servers that are not explicitly declared in the workflow's `tools:` frontmatter. Two possible approaches:

1. **Preferred:** Make auto-discovered MCP servers (from `.mcp.json`) non-fatal for agentic workflows that don't declare them in `tools:` — treat them as best-effort
2. **Alternative:** Support an `optional: true` flag per MCP server in `.mcp.json`, so repos can mark servers that should not block workflows on failure

## Impact

Any repo with a `.mcp.json` that includes servers requiring Docker, local secrets, or external connectivity will break all scheduled agentic workflows — even workflows that have no dependency on those servers.