Add BitRouter to Guardrails, Security & Governance

[SPIKESPIGEL404]

Adds BitRouter to Guardrails, Security & Governance — a direct peer to LiteLLM, Portkey Gateway, and AgentGateway already listed there. BitRouter is an open-source (Apache-2.0) agent-native LLM router that optimizes your agent with every run — zero harness changes, with every model call reliable, traceable, secure, and cost-effective — providing a single local control point with cross-protocol routing, an MCP gateway, guardrails, and multi-account failover.

• Edited data/projects.yaml only; regenerated README.md + README_zh.md via scripts/render_readme.py.
• scripts/verify_catalog.py passes (report committed).
• stars_snapshot set to the current GitHub count (166) and updated_at to today, rather than running a full sync_github_metadata.py (which would re-fetch every entry and bloat the diff). Happy to run the full sync if you'd prefer.

Checklist

• Link reachable
• Category correct (peer to LiteLLM/Portkey/AgentGateway)
• Summary concise and practical (EN + ZH)
• Renders cleanly in both READMEs
• Verification passes