Add MCP connection manager contract

[chubes4]

Summary

• Adds a generic MCP server registry and request-local connection manager contract in Data Machine core.
• Provides public helpers for registering servers, reading redacted config/state, connecting through an adapter hook, restarting, and cleanup.
• Keeps the slice transport-agnostic because this repo does not include a concrete MCP client/server package or transport runtime.

Refs #1043.

Scope note

This is the first contract seam for #1043, not the full persistent MCP server lifecycle/pooling implementation. It gives plugins a Data Machine-owned registration and connector surface without closing the issue.

Follow-up slice

• Wire Intelligence into datamachine_mcp_connector so its existing bridge/runtime can consume the Data Machine seam.
• Extract the reusable Intelligence bridge/runtime pieces into Data Machine core once the adapter boundary is proven.
• Then add persistent process lifecycle/pooling around the real runtime pieces instead of stubbing a fake transport.

Testing

• php tests/mcp-connection-manager-smoke.php
• composer lint -- --standard=phpcs.xml.dist inc/Engine/MCP tests/mcp-connection-manager-smoke.php
• php -l inc/Engine/MCP/MCPServerRegistry.php
• php -l inc/Engine/MCP/MCPConnectionManager.php
• php -l inc/Engine/MCP/functions.php
• php -l tests/mcp-connection-manager-smoke.php

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: implementing and testing the focused MCP connection manager: persistent server lifecycle and connection pooling #1043 MCP manager slice; Chris remains responsible for review.

[homeboy-ci]

Homeboy Results — data-machine

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since 9caa8a9

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-lint-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-lint-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26334623435

Test

✅ test — passed

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since 9caa8a9

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-test-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-test-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26334623435

Audit

✅ audit — passed

• requested_detectors — 2 finding(s)
• Total: 2 finding(s)

Deep dive: homeboy audit data-machine --changed-since 9caa8a9

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-audit-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26334623435

Tooling versions

• Homeboy CLI: homeboy 0.197.2+ae140d73
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: dd23ee80
• Action: unknown@unknown