Agent integration missing: Kimchi coding agent CLI

Orca recognizes many CLI coding agents (Claude Code, Codex, Gemini, OpenCode, pi/OMP, Prime, Cursor, ...) with terminal-title detection, hook-driven status, sidebar rows, settings catalog entries, and session resume.

**Kimchi** (the pi-compatible coding-agent harness) is not recognized today.

## Impact
- Kimchi panes show no agent-derived titles or status rows
- No hook-driven running/done status fed into the unified agent-hooks pipeline
- No completion notifications for top-level Kimchi runs
- No Kimchi entries in Settings > Agents or the agent catalog
- No session-resume wiring for Kimchi sessions

## Expected
Detect Kimchi as a pi-compatible agent across the existing pipeline: `agent-kind`, `pi-agent-kind`, hook listener + relay, synthetic titles, terminal-title detection, TUI agent config/catalog, session resume, and completion notifications that correctly ignore Kimchi **sub-agent** sessions (the harness marks them with `KIMCHI_SUBAGENT=1`).

Trace existing pi-compatible agent handling through agent-kind, pi-agent-kind, the hook listener and relay, synthetic and terminal-title handling, TUI agent config/catalog, session resume, and completion notifications. Compare each path with an existing pi-compatible agent, then verify Kimchi is recognized while sessions marked KIMCHI_SUBAGENT=1 are excluded.

Written by the indexing model from the issue text.