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/runtime/codex/instructions.md

@@ -0,0 +1,13 @@
+# Mosaic Runtime Adapter — Codex
+
+## MANDATORY — Read Before Any Response
+
+BEFORE responding to any user message, READ:
+
+1. `~/.config/mosaic/AGENTS.md`
+2. `~/.config/mosaic/runtime/codex/RUNTIME.md`
+
+Do NOT respond until both files are loaded.
+
+This file (`~/.codex/instructions.md`) exists only as a fallback for direct `codex` launches.
+For full injection, use `mosaic codex`.