feat: integrate framework files into monorepo under packages/mosaic/framework/

Moves all Mosaic framework runtime files from the separate bootstrap repo
into the monorepo as canonical source. The @mosaic/mosaic npm package now
ships the complete framework — bin scripts, runtime configs, tools, and
templates — enabling standalone installation via npm install.

Structure:
  packages/mosaic/framework/
  ├── bin/          28 CLI scripts (mosaic, mosaic-doctor, mosaic-sync-skills, etc.)
  ├── runtime/      Runtime adapters (claude, codex, opencode, pi, mcp)
  ├── tools/        Shell tooling (git, prdy, orchestrator, quality, etc.)
  ├── templates/    Agent and repo templates
  ├── defaults/     Default identity files (AGENTS.md, STANDARDS.md, SOUL.md, etc.)
  ├── install.sh    Legacy bash installer
  └── remote-install.sh  One-liner remote installer

Key files with Pi support and recent fixes:
- bin/mosaic: launch_pi() with skills-local loop
- bin/mosaic-doctor: --fix auto-wiring for all 4 harnesses
- bin/mosaic-sync-skills: Pi as 4th link target, symlink-aware find
- bin/mosaic-link-runtime-assets: Pi settings.json patching
- bin/mosaic-migrate-local-skills: Pi skill roots, symlink find
- runtime/pi/RUNTIME.md + mosaic-extension.ts

Package ships 251 framework files in the npm tarball (278KB compressed).

packages/mosaic/framework/tools/git/milestone-close.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+# milestone-close.sh - Close a milestone on GitHub or Gitea
+# Usage: milestone-close.sh -t <title>
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/detect-platform.sh"
+
+# Parse arguments
+TITLE=""
+
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        -t|--title)
+            TITLE="$2"
+            shift 2
+            ;;
+        -h|--help)
+            echo "Usage: milestone-close.sh -t <title>"
+            echo ""
+            echo "Options:"
+            echo "  -t, --title   Milestone title (required)"
+            echo "  -h, --help    Show this help"
+            exit 0
+            ;;
+        *)
+            echo "Unknown option: $1"
+            exit 1
+            ;;
+    esac
+done
+
+if [[ -z "$TITLE" ]]; then
+    echo "Error: Milestone title is required (-t)"
+    exit 1
+fi
+
+detect_platform
+
+if [[ "$PLATFORM" == "github" ]]; then
+    gh api -X PATCH "/repos/{owner}/{repo}/milestones/$(gh api "/repos/{owner}/{repo}/milestones" --jq ".[] | select(.title==\"$TITLE\") | .number")" -f state=closed
+    echo "Closed GitHub milestone: $TITLE"
+elif [[ "$PLATFORM" == "gitea" ]]; then
+    tea milestone close "$TITLE"
+    echo "Closed Gitea milestone: $TITLE"
+else
+    echo "Error: Unknown platform"
+    exit 1
+fi