devrig: MCP Steroid Goes Level 3 — Autonomous IDE Setup for AI Agents

The new `devrig` CLI in MCP Steroid 0.100 turns the IDE bring-up ritual into one stdio command. `devrig install ` writes the MCP config; `devrig backend download/start` brings an IntelliJ-family IDE into existence and gives the agent an IDE of its own. In the e2e test, Claude provisions an IDE and finds 4,633 PSI usages of one class in Keycloak — in one prompt.