feat!: unify mosaic CLI — native launcher, no bin/ directory

BREAKING CHANGE: ~/.config/mosaic/bin/ is removed entirely.
The mosaic npm CLI is now the only executable.

## What changed

- **bin/ → deleted**: All scripts moved to tools/_scripts/ (internal)
- **mosaic-launch → deleted**: Launcher logic is native TypeScript
  in packages/cli/src/commands/launch.ts
- **mosaic.ps1 → deleted**: PowerShell launcher removed
- **Framework install.sh**: Complete rewrite with migration system
- **Version tracking**: .framework-version file (schema v2)
- **Migration v1→v2**: Auto-removes bin/, cleans old PATH entries
  from shell profiles

## Native TypeScript launcher (commands/launch.ts)

All runtime launch logic ported from bash:
- Runtime prompt builder (AGENTS.md + RUNTIME.md + USER.md + TOOLS.md)
- Mission context injection (reads .mosaic/orchestrator/mission.json)
- PRD status injection (scans docs/PRD.md)
- Pre-flight checks (MOSAIC_HOME, AGENTS.md, SOUL.md, runtime binary)
- Session lock management with signal cleanup
- Per-runtime launch: Claude, Codex, OpenCode, Pi
- Yolo mode flags per runtime
- Pi skill discovery + extension loading
- Framework management (init, doctor, sync, bootstrap) delegates
  to tools/_scripts/ bash implementations

## Installer

- tools/install.sh: detects framework by .framework-version or AGENTS.md
- Framework install.sh: migration system with schema versioning
- Forward-compatible: add migrations as numbered blocks
- No PATH manipulation for framework (npm bin is the only PATH entry)

packages/mosaic/framework/tools/_scripts/mosaic-wizard

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# mosaic-wizard — Thin shell wrapper for the bundled TypeScript wizard
+MOSAIC_HOME="${MOSAIC_HOME:-$HOME/.config/mosaic}"
+
+# Look for the bundle in the installed location first, then the source repo
+WIZARD_BIN="$MOSAIC_HOME/dist/mosaic-wizard.mjs"
+if [[ ! -f "$WIZARD_BIN" ]]; then
+  WIZARD_BIN="$(cd "$(dirname "$0")/.." && pwd)/dist/mosaic-wizard.mjs"
+fi
+
+if [[ ! -f "$WIZARD_BIN" ]]; then
+  echo "[mosaic-wizard] ERROR: Wizard bundle not found." >&2
+  echo "[mosaic-wizard] Re-install with: npm install -g @mosaic/mosaic" >&2
+  exit 1
+fi
+
+if ! command -v node >/dev/null 2>&1; then
+  echo "[mosaic-wizard] ERROR: Node.js is required but not found." >&2
+  echo "[mosaic-wizard] Install Node.js 18+ from https://nodejs.org" >&2
+  exit 1
+fi
+
+exec node "$WIZARD_BIN" "$@"