refactor(api+cli): registry-driven endpoints + CLI auto-update from mcp_tool_registry

[bryanfawcett]

DB status: ✅ COMPLETE — frontend work remaining

All DB work done. The registry and helpers required by this issue already exist (see #82 for the migration manifest).

Node language update

All API routes at app/api/v1/* that reference architecture_layer must be updated to ecosystem_node. The list_components RPC parameter changed from p_layer (text) to p_node (integer). Update all API route handlers accordingly.

CLI auto-update note

The @nyuchi/design-cli auto-update from mcp_tool_registry (see #81) should reference mcp.nyuchi.dev/design as the MCP server base URL — not design.nyuchi.com/mcp. Update the CLI's MCP server URL constant when implementing the registry-driven endpoints.

[linear]

FRD-32