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/templates/docs/PRD.md.template

@@ -0,0 +1,75 @@
+# PRD: {PROJECT_OR_FEATURE_NAME}
+
+## Metadata
+
+- Owner: {owner}
+- Date: {yyyy-mm-dd}
+- Status: draft|approved|in-progress|completed
+- Best-Guess Mode: true|false
+
+## Problem Statement
+
+{what problem is being solved and why now}
+
+## Objectives
+
+1. {objective-1}
+2. {objective-2}
+
+## Scope
+
+### In Scope
+
+1. {in-scope-item}
+
+### Out of Scope
+
+1. {out-of-scope-item}
+
+## User/Stakeholder Requirements
+
+1. {requirement}
+
+## Functional Requirements
+
+1. {functional-requirement}
+
+## Non-Functional Requirements
+
+1. Security: {requirements}
+2. Performance: {requirements}
+3. Reliability: {requirements}
+4. Observability: {requirements}
+
+## Acceptance Criteria
+
+1. {ac-1}
+2. {ac-2}
+
+## Constraints and Dependencies
+
+1. {constraint-or-dependency}
+
+## Risks and Open Questions
+
+1. Risk: {risk}
+2. Open Question: {question}
+
+## Testing and Verification Expectations
+
+1. Baseline checks: {lint/type/unit/integration expectations}
+2. Situational testing: {required situational checks}
+3. Evidence format: {how verification will be reported}
+
+## Milestone / Delivery Intent
+
+1. Target milestone/version: {e.g., 0.0.2}
+2. Definition of done: {completion conditions}
+
+## Assumptions
+
+List only if Best-Guess Mode is true.
+Prefix each entry with `ASSUMPTION:`.
+
+1. ASSUMPTION: {guessed decision and rationale}
+