Add Pi as a first-class detected AI agent so it appears in the IDE & AI Agents inventory

[varunsh-coder]

Summary

Pi is currently surfaced only through the Agent Skills view (discovery-driven) but is absent from the IDE & AI Agents view (curated inventory). We should add a first-class detector for Pi so it appears in both views.

Background

The agent has two independent detection paths:

1. Skills detection (internal/detector/skills.go) enumerates per-agent skill directories. Pi is already a recognized skill source:

   • Global: ~/.pi/agent/skills → pi_user → agent pi (skills.go:304)
   • Per-project: <project>/.pi/skills → pi_project → agent pi (skills.go:344)
   • Project marker: .pi → skills (skills.go:364)

   Because of this, Pi skills show up in the Agent Skills view.

2. AI agent / IDE detection uses four curated registries, and Pi is present in none of them:

   • internal/detector/aicli.go — cliToolDefinitions
   • internal/detector/agent.go — agentDefinitions
   • internal/detector/framework.go — frameworkDefinitions
   • internal/detector/ide.go — ideDefinitions

   A grep for pi / .pi across these four files returns no matches.

Why this happens (and why it's currently correct)

The AI-agent registries follow an "install-proof" philosophy (see internal/detector/agent.go:89-96): a config directory alone is intentionally not treated as proof of installation, to avoid phantom entries from stale dotfiles. First-class agents require a real binary on PATH. Pi has no such detector, so it correctly does not appear as an installed agent today — it's only inferred from its skill files.

Proposed change

Add a Pi detector entry to the appropriate registry (most likely cliToolDefinitions in internal/detector/aicli.go, matching how the Pi CLI is installed). Needed:

• Binary name(s) / install path(s) Pi ships as
• Vendor label
• Agent type (cli_tool vs general_agent)
• Version-detection command, if available

Once detected, Pi will show up in the IDE & AI Agents inventory alongside the existing skills-based data, giving consistent coverage across both views.

Notes

• The pi agent label already exists in the skill-record model enum (internal/model/model.go:712), so no model change is needed for the skills side.
• Confirm the exact Pi install footprint before choosing the registry and match rules.