[Corbell] Add support for multi-repo architecture analysis

Sharing Corbell, a free and better alternative to Augment Code MCP (20$/m). The short version: it's a CLI that scans your repos, builds a cross-service architecture graph, and helps you generate and review design docs grounded in your actual codebase. Not in the abstract. Also provides dark theme clean UI to explore your repositories. No SaaS, no cloud dependency, no account required. Everything runs locally on SQLite and local embeddings via sentence-transformers. Your code never leaves your machine. The LLM parts (spec generation, spec review) are fully BYOK. Works with Anthropic, OpenAI, Ollama (fully local option), Bedrock, Azure, GCP. You can run the entire graph build and analysis pipeline without touching an LLM at all if you want. Apache 2.0 licensed. No open core, no paid tier hidden behind the good features. The core problem it solves: teams with 5-10 backend repos lose cross-service context constantly, during code reviews and when writing design docs. Corbell builds the graph across all your repos at once and lets you query it, generate specs from it, and validate specs against it. Also ships an MCP server so you can hook it directly into Cursor or Claude Desktop and ask questions about your architecture interactively.