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-ensure-excalidraw

@@ -0,0 +1,119 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+MOSAIC_HOME="${MOSAIC_HOME:-$HOME/.config/mosaic}"
+TOOLS_DIR="$MOSAIC_HOME/tools/excalidraw"
+MODE="apply"
+SCOPE="user"
+
+err() { echo "[mosaic-excalidraw] ERROR: $*" >&2; }
+log() { echo "[mosaic-excalidraw] $*"; }
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --check) MODE="check"; shift ;;
+    --scope)
+      if [[ $# -lt 2 ]]; then
+        err "--scope requires a value: user|local"
+        exit 2
+      fi
+      SCOPE="$2"
+      shift 2
+      ;;
+    *)
+      err "Unknown argument: $1"
+      exit 2
+      ;;
+  esac
+done
+
+require_binary() {
+  local name="$1"
+  if ! command -v "$name" >/dev/null 2>&1; then
+    err "Required binary missing: $name"
+    return 1
+  fi
+}
+
+check_software() {
+  require_binary node
+  require_binary npm
+}
+
+check_tool_dir() {
+  [[ -d "$TOOLS_DIR" ]] || { err "Tool dir not found: $TOOLS_DIR"; return 1; }
+  [[ -f "$TOOLS_DIR/package.json" ]] || { err "package.json not found in $TOOLS_DIR"; return 1; }
+  [[ -f "$TOOLS_DIR/launch.sh" ]] || { err "launch.sh not found in $TOOLS_DIR"; return 1; }
+}
+
+check_npm_deps() {
+  [[ -d "$TOOLS_DIR/node_modules/@modelcontextprotocol" ]] || return 1
+  [[ -d "$TOOLS_DIR/node_modules/@excalidraw" ]] || return 1
+  [[ -d "$TOOLS_DIR/node_modules/jsdom" ]] || return 1
+}
+
+install_npm_deps() {
+  if check_npm_deps; then
+    return 0
+  fi
+  log "Installing npm deps in $TOOLS_DIR..."
+  (cd "$TOOLS_DIR" && npm install --silent) || {
+    err "npm install failed in $TOOLS_DIR"
+    return 1
+  }
+}
+
+check_claude_config() {
+  python3 - <<'PY'
+import json
+from pathlib import Path
+
+p = Path.home() / ".claude.json"
+if not p.exists():
+    raise SystemExit(1)
+try:
+    data = json.loads(p.read_text(encoding="utf-8"))
+except Exception:
+    raise SystemExit(1)
+mcp = data.get("mcpServers")
+if not isinstance(mcp, dict):
+    raise SystemExit(1)
+entry = mcp.get("excalidraw")
+if not isinstance(entry, dict):
+    raise SystemExit(1)
+cmd = entry.get("command", "")
+if not cmd.endswith("launch.sh"):
+    raise SystemExit(1)
+PY
+}
+
+apply_claude_config() {
+  require_binary claude
+  local launch_sh="$TOOLS_DIR/launch.sh"
+  claude mcp add --scope user excalidraw -- "$launch_sh"
+}
+
+# ── Check mode ────────────────────────────────────────────────────────────────
+
+if [[ "$MODE" == "check" ]]; then
+  check_software
+  check_tool_dir
+  if ! check_npm_deps; then
+    err "npm deps not installed in $TOOLS_DIR (run without --check to install)"
+    exit 1
+  fi
+  if ! check_claude_config; then
+    err "excalidraw not registered in ~/.claude.json"
+    exit 1
+  fi
+  log "excalidraw MCP is configured and available"
+  exit 0
+fi
+
+# ── Apply mode ────────────────────────────────────────────────────────────────
+
+check_software
+check_tool_dir
+install_npm_deps
+apply_claude_config
+log "excalidraw MCP configured (scope: $SCOPE)"