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-upgrade-slaves

@@ -0,0 +1,116 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+MOSAIC_HOME="${MOSAIC_HOME:-$HOME/.config/mosaic}"
+BOOTSTRAP_CMD="$MOSAIC_HOME/tools/_scripts/mosaic-bootstrap-repo"
+
+roots=("$HOME/src")
+apply=0
+
+usage() {
+  cat <<USAGE
+Usage: $(basename "$0") [options]
+
+Upgrade all Mosaic-linked slave repositories by re-running repo bootstrap with --force.
+
+Options:
+  --root <path>   Add a search root (repeatable). Default: $HOME/src
+  --apply         Execute upgrades. Without this flag, script is dry-run.
+  -h, --help      Show this help
+USAGE
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --root)
+      [[ $# -lt 2 ]] && { echo "Missing value for --root" >&2; exit 1; }
+      roots+=("$2")
+      shift 2
+      ;;
+    --apply)
+      apply=1
+      shift
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    *)
+      echo "Unknown argument: $1" >&2
+      usage >&2
+      exit 1
+      ;;
+  esac
+done
+
+if [[ ! -x "$BOOTSTRAP_CMD" ]]; then
+  echo "[mosaic-upgrade] Missing bootstrap command: $BOOTSTRAP_CMD" >&2
+  echo "[mosaic-upgrade] Install/refresh framework first: ~/.config/mosaic/install.sh" >&2
+  exit 1
+fi
+
+# De-duplicate roots while preserving order.
+uniq_roots=()
+for r in "${roots[@]}"; do
+  skip=0
+  for e in "${uniq_roots[@]}"; do
+    [[ "$r" == "$e" ]] && { skip=1; break; }
+  done
+  [[ $skip -eq 0 ]] && uniq_roots+=("$r")
+done
+
+candidates=()
+for root in "${uniq_roots[@]}"; do
+  [[ -d "$root" ]] || continue
+
+  while IFS= read -r marker; do
+    repo_dir="$(dirname "$(dirname "$marker")")"
+    if [[ -d "$repo_dir/.git" ]]; then
+      candidates+=("$repo_dir")
+    fi
+  done < <(find "$root" -type f -path '*/.mosaic/README.md' 2>/dev/null)
+done
+
+# De-duplicate repos while preserving order.
+repos=()
+for repo in "${candidates[@]}"; do
+  skip=0
+  for existing in "${repos[@]}"; do
+    [[ "$repo" == "$existing" ]] && { skip=1; break; }
+  done
+  [[ $skip -eq 0 ]] && repos+=("$repo")
+done
+
+count_total=${#repos[@]}
+count_ok=0
+count_fail=0
+
+mode="DRY-RUN"
+[[ $apply -eq 1 ]] && mode="APPLY"
+
+echo "[mosaic-upgrade] Mode: $mode"
+echo "[mosaic-upgrade] Roots: ${uniq_roots[*]}"
+echo "[mosaic-upgrade] Linked repos found: $count_total"
+
+if [[ $count_total -eq 0 ]]; then
+  exit 0
+fi
+
+for repo in "${repos[@]}"; do
+  if [[ $apply -eq 1 ]]; then
+    if "$BOOTSTRAP_CMD" "$repo" --force >/dev/null; then
+      echo "[mosaic-upgrade] upgraded: $repo"
+      count_ok=$((count_ok + 1))
+    else
+      echo "[mosaic-upgrade] FAILED: $repo" >&2
+      count_fail=$((count_fail + 1))
+    fi
+  else
+    echo "[mosaic-upgrade] would upgrade: $repo"
+  fi
+done
+
+if [[ $apply -eq 1 ]]; then
+  echo "[mosaic-upgrade] complete: ok=$count_ok failed=$count_fail total=$count_total"
+  [[ $count_fail -gt 0 ]] && exit 1
+fi