fix: add cursor agent support

[bgoosmanviz]

No description provided.

[roborev-ci]

roborev: Combined Review (ffc4cc5)

Verdict: The PR adds support for mapping the "agent" CLI command to the "cursor" agent
, but requires a high-priority fix for a compilation error in the tests.

High Severity

• internal/agent/agent_test.go (Lines 45-46)
  • Problem: TestCanonicalNameAliases attempts to call CanonicalName(), but the actual
    function handling alias resolution in internal/agent/agent.go is unexported and named resolveAlias(). This will result in a compilation error.
  • Fix: Change CanonicalName(tt.input) to resolveAlias(tt.input) inside the test loop.

---

Synthesized from 3 reviews (agents: codex, gemini | types: default, security)

[mariusvniekerk]

Given how this issue arose we need more validation on the config /params for agents. Returning an error for an unknown explicitly asked for agent feels appropriate