chore: scaffold mosaic monorepo (Phase 0)

- pnpm workspaces + Turborepo
- tsconfig.base.json strict ESM
- @mosaic/types stub package
- Woodpecker CI pipeline with Valkey service
- docs/PRD.md, docs/TASKS.md, CONTEXT.md

CONTEXT.md

@@ -0,0 +1,17 @@
+# Mosaic Monorepo Context
+
+This repository (`mosaic/mosaic`) is the canonical monorepo for all `@mosaic/*` packages.
+
+## Wave Structure
+
+- Wave 1 (Foundation): establish shared workspace/tooling and migrate `@mosaic/types` + `@mosaic/queue`
+- Wave 2 (Entry Point): migrate install wizard (`@mosaic/mosaic`) and plugin (`@mosaic/openclaw-context`)
+- Wave 3 (Rewrites): rewrite shell-first tools as TypeScript packages (`coord`, `prdy`, `quality-rails`, `cli`)
+
+## Key Package Layout
+
+- `packages/types`: shared type contracts
+- `packages/queue`: queue package (migration target)
+- `packages/mosaic`: install wizard package (migration target)
+- `packages/coord`, `packages/prdy`, `packages/quality-rails`, `packages/cli`: future TypeScript rewrites
+- `plugins/openclaw-context`: OpenClaw plugin package