[13.2 Docs] Rename 'aspire mcp' CLI reference docs to 'aspire agent'

[joperezr]

Summary

The aspire mcp command has been renamed to aspire agent in Aspire 13.2. The CLI reference documentation still uses the old aspire mcp command names and needs to be updated.

Current State

The following doc pages exist under src/frontend/src/content/docs/reference/cli/commands/ and reference the old name:

• aspire-mcp.mdx — parent command page
• aspire-mcp-init.mdx — aspire mcp init subcommand
• aspire-mcp-start.mdx — aspire mcp start subcommand

Additionally, get-started/configure-mcp.mdx and dashboard/mcp-server.mdx may also reference the old command name.

What's Needed

1. Create new pages (or rename existing ones):

   • aspire-agent.mdx — parent command for aspire agent
   • aspire-agent-mcp.mdx — aspire agent mcp subcommand (starts the MCP server)
   • aspire-agent-init.mdx — aspire agent init subcommand (initializes agent environment configuration)

2. Update all references across the docs site from aspire mcp to aspire agent.

3. Verify sidebar/navigation configuration reflects the new command structure.

Context

• Feature introduced in Aspire 13.2
• Covered in the What's new in 13.2 notes
• The rename better reflects the purpose of managing AI agent integrations, not just MCP specifically