Add Cursor CLI agent support (Composer 2.5 / Grok 4.5)

[vivek100]

Problem

Supabase evals already support Claude Code, Codex, OpenCode, and the in-process AI SDK agent, but not Cursor’s CLI agent (cursor-agent). We want to run the same tools-mode / skills comparisons against Composer 2.5 and Grok 4.5.

Proposal

Add a Cursor CLI harness in the same shape as peer agents:

• Runner — pinned official install, CURSOR_API_KEY, headless --print --output-format=stream-json (+ --yolo --trust --approve-mcps)
• Parser — stream-json → shared TranscriptEvents
• Experiments — baseline + no-skills for both models (Supabase MCP on, matching Claude Code)

Model ids from live cursor-agent --list-models: composer-2.5, cursor-grok-4.5-high.

Acceptance

• Cursor agent registered and callable via cursorAgent({ model })
• Four experiments: composer/grok × skills / no-skills
• Unit tests for runner/parser
• Document CURSOR_API_KEY in .env.example
• Tools-mode smoke shows Supabase MCP tool use in the transcript

Related

Implementation PR: #166

[vivek100]

Implementation: #166