feat: ship Claude Code plugin in-tree

[singaraiona]

Summary

• Ship raysense as an installable Claude Code plugin alongside the crate. Marketplace manifest at the repo root; plugin sources under ./claude-plugin/. Same physical layout as sentrux uses.
• Four phase-scoped skills mapped to the agent's edit cycle (raysense-bootstrap / raysense-impact / raysense-verify / raysense-audit). Each is a short markdown playbook over MCP tools already exposed by src/mcp.rs:137.
• Zero new Rust code — every raysense_* tool referenced across the four SKILL.md files resolves in the existing tool registry. cargo test still 123/123 green.

Multi-codebase isolation

cwd-driven, no global state. Each skill passes path: $CWD to every MCP call; per-project state lives in <repo>/.raysense/. Two CC sessions on two repos = two raysense --mcp processes, two on-disk state trees, zero cross-project bleed.

Install path

cargo install raysense
/plugin marketplace add RayforceDB/raysense
/plugin install raysense

Out of scope (deferred to v2)

• Slash commands (/raysense-bootstrap, etc.) — manual reinforcement when agent forgets
• SessionStart / Stop hooks — deterministic auto-fire
• agents/raysense-analyst.md sub-agent — context isolation for noisy audits
• Cross-platform packaging (Codex, generic MCP clients)

Test plan

• cargo fmt --check clean
• cargo test — 123/123 green
• All three JSON files parse with jq
• All 19 distinct raysense_* names referenced in skills exist in tools_list (src/mcp.rs:137)
• Name-scan: no vendor/reference-project mentions in tracked files
• End-to-end: /plugin marketplace add <local path> → /plugin install raysense → confirm bootstrap activates and writes .raysense/baseline/ + populated tables/
• Verify: make a small structural regression, trigger raysense-verify, confirm baseline_diff reports it
• Multi-repo: repeat in a second repo, confirm .raysense/ directories stay independent