MCP server: phase 3 - governance, resources, and prompts

Features

• MCP server: phase 3 - governance, resources, and prompts
• MCP server: CI integration, public npm publishing, and docs

Fixes

• Portal: remove queued page checkboxes and reorganize mailbox sidebar
• Outcomes: fix ingest 500 and segment-check 500 errors
• Threads: reply messages now appear in thread history
• Send: block sends with invalid template slugs and return correct duplicate status