feat: add Oh My Pi (omp) agent support

[FelipeMayerDev]

Summary

Adds Oh My Pi (omp) as the 11th supported agent in HarnessKit.

Backend

• New OmpAdapter for ~/.omp / ~/.omp/agent layout.
• Discovers user/project skills:
  • ~/.omp/agent/skills/<name>/SKILL.md
  • .omp/skills/<name>/SKILL.md
• Discovers MCP config:
  • ~/.omp/agent/mcp.json
  • .omp/mcp.json
  • JSON mcpServers format, including stdio command, remote url, args, env, and native enabled flag.
• Discovers TypeScript/JavaScript extension modules as plugins:
  • ~/.omp/agent/extensions/*.{ts,js,mjs,cjs}
  • .omp/extensions/
• Discovers native config/rules:
  • AGENTS.md, RULES.md, config.yml, settings.json.
• Declares HookFormat::None because omp hooks are JS/TS event modules, not shell-command hook configs (same model as OpenCode).

Frontend

• Adds omp to AGENT_ORDER and display names.
• Adds theme color variables and extension filter colors.
• Adds an Oh My Pi mascot using the official omp.sh/favicon.svg π logo (pink→purple→cyan gradient).
• Updates onboarding layout for the new agent.

Docs

• Updates English and Chinese README agent count and capability matrix.

Verification

• cargo check -p hk-core ✅
• cargo test -p hk-core ✅ — 557 tests passed
• npx tsc --noEmit ✅
• npx vitest run src/lib/__tests__/types.test.ts src/stores/__tests__/extension-helpers.test.ts ✅ — 76 tests passed
• Manual smoke test against a real ~/.omp install ✅
  • detected omp
  • read ~/.omp/agent/config.yml
  • discovered 3 real extension modules: orca-agent-status, orca-prefill, orca-titlebar-spinner

Screenshots

Overview — Oh My Pi detected

Agent details — Oh My Pi

Extensions filtered by Oh My Pi

Oh My Pi mascot card crop